Radiation-sensitive resin composition

ABSTRACT

A radiation-sensitive resin composition including (A) a resin containing an alicyclic skeleton in its backbone, and (B) a radiation-sensitive acid-generating agent, is provided. This composition is excellent in transparency with respect to radiation and dry etching resistance, and can give a photoresist pattern excellent in adhesion to substrates, sensitivity, resolution, and developability.

This application is a Continuation of application Ser. No. 08/797,620filed on Feb. 7, 1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radiation-sensitive resincomposition, and particularly to a radiation-sensitive resin compositionwhich can be favorably used as a chemically amplified photoresist usefulin micro-processing using various radiations, e.g., far-ultravioletradiation such as KrF excimer laser or ArF excimer laser, X rays such assynchrotron radiation, charged particle radiation such as electron beam,etc.

2. Description of the Prior Art

In the field of micro-processing represented by fabrication ofintegrated circuit elemental devices, to realize a higher degree ofintegration, lithography technology capable of micro-processing on theorder of sub-half micron (0.25 μm or less) is recently underdevelopment, and it is expected that micro-processing on the order ofsub-quarter micron (0.25 μm or less) will be required in the nearfuture.

In the conventional lithography processing, near ultra-violet radiationsuch as i-line and the like are used as radiation. However, it is saidto be extremely difficult to realize micro-processing on the order ofsub-quarter micron with near ultra-violet radiation.

Thus, to enable micro-processing on the order of sub-quarter micron, theuse of radiations with shorter wave lengths is considered. Radiationshaving such short wave lengths include, for example, a bright linespectrum of mercury lamps, far-ultraviolet radiations represented byexcimer lasers, X rays, electron beam, etc. Out of these, KrF excimerlaser or ArF excimer laser attracts particular attention.

As a radiation-sensitive resin composition suited for irradiation withexcimer lasers, there have been proposed many compositions (hereinafter,referred to as “chemically amplified radiation-sensitive composition”)using chemical amplification action effected by a component containingan acid-cleavable functional group and a component which generates anacid upon irradiation with radiation (hereinafter, referred to as“acid-generating agent”).

For example, Japanese Patent Publication (kokoku) No. 2-27660 discloses,as one of the chemically amplified radiation-sensitive compositions, acomposition comprising a polymer having a t-butyl ester group of acarboxylic acid or a t-butyl carbonate group of a phenol, and anacid-generating agent. This composition uses the phenomenon that thet-butyl ester group or the t-butyl carbonate group present in thepolymer cleaves by the catalytic action of an acid generated byirradiation, so that the polymer comes to have acidic groups of carboxylor phenol group, and the irradiated areas of the photoresist filmthereby become readily soluble in alkaline developing solution.

Most of the chemically amplified radiation-sensitive compositions knownheretofore, are based on a phenolic resin. The phenolic resin has adrawback that when far ultraviolet radiation is used as radiation, thefar ultraviolet radiation is absorbed by aromatic rings in the resin,and therefore the far ultraviolet radiation can not reach the lowerportion near the substrate of the photoresist film sufficiently. Forthis, irradiation dose is larger at the upper portion of the photoresistfilm but on the other hand it is smaller at the lower portion, resultingin the problem that the photoresist pattern after development forms atapered resist profile, that is, the width is smaller at the upperportion and become larger at the lower portion. This means thatsufficient resolution can not be obtained. It is also a problem that ifthe developed photoresist pattern is tapered, desired dimensionalaccuracy can not be achieved at subsequent steps, i.e., at the steps ofetching, ion implantation, etc. Furthermore, if the upper portion of thephotoresist pattern in section is not rectangular, the rate of loss ofthe photoresist caused by dry etching is increased, so that the etchingconditions can be controlled with difficulty.

The shape of a photoresist pattern in section can be improved byincreasing the transmittance of the photoresist film with respect toradiation. For example, since (meth)acrylate resins represented bypolymethyl methacrylate have a high transparency with respect to farultraviolet radiation, they are very favorable resins from the viewpointof transmittance of radiation. For example, Japanese Laid-open PatentPublication (kokai) No. 4-226461 discloses a chemically amplifiedradiation-sensitive resin composition using a methacrylate resin.Although this composition is excellent in performance ofmicro-processing, it has a drawback of poor dry etching resistancebecause it contains no aromatic rings. Also, in this case, etchingprocessing with high accuracy can be conducted with difficulty.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide aradiation-sensitive resin composition which is particularly excellent intransparency with respect to radiation and dry etching resistance andwhich can give a photoresist pattern excellent in adhesion tosubstrates, sensitivity, resolution, developability, etc., as achemically amplified photoresist sensitive to activated radiations, forexample, far ultraviolet radiation represented by KrF excimer laser orArf excimer laser.

The present invention provides a radiation-sensitive resin compositioncomprising (A) a resin containing an alicyclic skeleton in the backbone,and (B) a radiation-sensitive acid-generating agent capable ofgenerating an acid upon irradiation.

The radiation-sensitive resin composition of the present invention is,as a chemically amplified photoresist, excellent particularly intransparency for radiation and dry etching resistance, and can form aphotoresist pattern excellent in adhesion to substrates, sensitivity,resolution and developability. The composition can be very suitably usedin the production of semiconductor devices of which miniaturization willfurther proceed in the future.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following terms are herein used to generically have the meaningbelow.

The term “(cyclo)alkane” includes alkane and cycloalkane, “(cyclo)alkyl”includes alkyl and cycloalkyl, “(cyclo)alkoxy” includes alkoxy andcycloalkoxy, and “(cyclo)acyl” includes acyl and cycloalkylcarbonyl.

The term “(meth)acrylic acid” includes acrylic acid and methacrylicacid, and “(meth)acrylate” includes acrylate and methacrylate.

The term “(co)polymer” includes homopolymer and copolymer, and“(co)polymerization” includes homopolymerization and copolymerization.

The present invention will now be described in detail.

Resin (A)

The alicyclic skeleton contained in the resin comprising an alicyclicskeleton in the backbone (hereinafter, referred to as “resin (A)”) maybe monocyclic as in the skeletons derived from cycloalkanes orpolycyclic as in the skeletons derived from bicyclo[2.2.1]heptane,tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecane or the like. The resin (A)may contain one or more kinds of alicyclic skeletons.

Said alicyclic skeleton may contain at least one group which is cleavedby an acid (hereinafter, referred to as “acid-cleavable group”) at anyposition thereon. The alicyclic skeleton may optionally contain one ormore substituents other than the acid-cleavable group, e.g., a halogenatom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, amonovalent halogenated hydrocarbon group having 1 to 10 carbon atoms atany position thereon.

The use of the resin (A) comprising an alicyclic skeleton in thebackbone according to the present invention, has been able to provide aradiation-sensitive resin composition which is particularly excellent intransparency with respect to radiation and dry etching resistance, andwhich can give a photoresist pattern excellent in adhesion tosubstrates, sensitivity, resolution, developability, etc., as aphotoresist.

The resin (A) used in the present invention is preferably a resin whichis insoluble or slightly soluble in alkali in itself but which has atleast one acid-cleavable group to be cleaved by the catalytic action ofan acid and becomes alkali-soluble. The terminology “insoluble orslightly soluble in alkali” herein means that the resin is insoluble orslightly soluble in a developing solution of an alkaline solution usedfor development of the photoresist film formed from theradiation-sensitive resin composition of the present invention. Thesolubility of the resin (A) in alkali can be regulated by the content ofacidic functional groups such as carboxyl groups.

Preferred alicyclic skeletons in the resin (A) include the skeletonrepresented by the following general formula (1) and the skeletonrepresented by the general formula (2), and the skeleton of the generalformula (1) is particularly preferred.

wherein in the general formula (1) and general formula (2), n is 0 or 1,A and B represent independently a hydrogen atom, a halogen atom, amonovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalenthalogenated hydrocarbon group having 1 to 10 carbon atoms, and X and Yrepresent independently a hydrogen atom, a halogen atom, a monovalenthydrocarbon group having 1 to 10 carbon atoms, a monovalent halogenatedhydrocarbon group having 1 to 10 carbon atoms or an acid-cleavablegroup, provided that at least one of X and Y is an acid-cleavable group.

Preferably, the acid-cleavable group of X and Y in the general formula(1) and general formula (2) is a group: —(CH₂)_(i)COOR¹, —(CH₂)_(i)OCOR²or —(CH₂)_(i)CN wherein R¹ is a hydrocarbon group having 1 to 10 carbonatoms, a halogenated hydrocarbon group having 1 to 10 carbon atoms, atetrahydrofuranyl group, a tetrahydropyranyl group, a carbobutoxymethylgroup, a carbobutoxyethyl group, a carbobutoxypropyl group or atrialkylsilyl group the alkyl groups of which each have 1 to 4 carbonatoms, R² represents a hydrocarbon group having 1 to 10 carbon atoms ora halogenated hydrocarbon group having 1 to 10 carbon atoms, and i is aninteger of 0 to 4; or X and Y are bonded to each other to form abivalent group represented by the formula:

wherein Z is —O— or —N(R³)— in which R³ is a hydrogen atom, a halogenatom, an alkyl group having 1 to 8 carbon atoms or a —SO₂R⁴ group having1 to 4 carbon atoms in which R⁴ is an alkyl group having 1 to 4 carbonatoms or a halogenated alkyl group having 1 to 4 carbon atoms,

or the formula: —O—, so that X and Y form, jointly with the two carbonatoms which constitute a part of the alicyclic skeleton and to which Xand Y are directly bonded, an oxygen-containing or nitrogen-containingheterocyclic structure having the formula:

where Z is as defined above.

In the preferable acid-cleavable groups of X and Y in the generalformula (1) and general formula (2), the group —(CH₂)_(i)COOR¹ includes,for example, (cyclo)alkoxycarbonyl groups such as methoxycarbonyl,ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl,2-methylpropoxycarbonyl, 1-methylpropoxycarbonyl, t-butoxycarbonyl,n-pentyloxycarbonyl, n-hexyloxycarbonyl, n-heptyloxycarbonyl,n-octyloxycarbonyl, n-decyloxycarbonyl, cyclopentyloxycarbonyl,cyclohexyloxycarbonyl, 4-t-butylcyclohexyloxycarbonyl,cycloheptyloxycarbonyl, and cyclooctyloxycarbonyl groups;aryloxycarbonyl groups such as phenoxycarbonyl,4-t-butylphenoxycarbonyl, and 1-naphthyloxycarbonyl groups;aralkyloxycarbonyl groups such as benzyloxycarbonyl, and4-t-butylbenzyloxycarbonyl groups; (cyclo)alkoxycarbonylmethyl groupssuch as methoxycarbonylmethyl, ethoxycarbonylmethyl,n-propoxycarbonylmethyl, isopropoxycarbonylmethyl,n-butoxycarbonylmethyl, 2-methylpropoxycarbonylmethyl,1-methylpropoxycarbonylmethyl, t-butoxycarbonylmethyl,cyclohexyloxycarbonylmethyl and 4-t-butylcyclohexyloxycarbonylmethylgroups; aryloxycarbonylmethyl groups such as phenoxycarbonylmethyl and1-naphthyloxycarbonylmethyl groups; aralkyloxycarbonylmethyl groups suchas benzyloxycarbonylmethyl and 4-t-butylbenzyloxycarbonylmethyl groups;(cyclo)alkoxycarbonylethyl groups such as 2-methoxycarbonylethyl,2-ethoxycarbonylethyl, 2-n-propoxycarbonylethyl,2-isopropoxycarbonylethyl, 2-n-butoxycarbonylethyl,2-(2-methylpropoxy)carbonylethyl, 2-(1-methylpropoxy)carbonylethyl,2-t-butoxycarbonylethyl, 2-cyclohexyloxycarbonylethyl and2-(4-butylcyclohexyloxycarbonyl)ethyl groups; 2-aryloxycarbonylethylgroups such as 2-phenoxycarbonylethyl and 2-(1-naphthylcarbonyl)ethylgroups; and 2-aralkyloxycarbonylethyl groups such as2-benzyloxycarbonylethyl and 2-(4-t-butylbenzyloxycarbonyl)ethyl groups.

Among these groups, preferred are groups corresponding to the group—COOR¹, more preferred are (cyclo)alkoxycarbonyl groups, andparticularly preferred are methoxycarbonyl, ethoxycarbonyl,n-butoxycarbonyl, t-butoxycarbonyl and cyclohexyloxycarbonyl groups.

The group —(CH₂)_(i)OCOR² includes, for example, a (cyclo)acyloxy groupsuch as acetyloxy, propionyloxy, butyryloxy, valeryloxy, caproyloxy,heptanoyloxy, octanoyloxy, nonanoyloxy, decanoyloxy, undecanoyloxy,cyclohexylcarbonyloxy and 4-t-butylcyclohexylcarbonyloxy; anarylcarbonyloxy group such as benzoyloxy, 4-t-butylbenzoyloxy and1-naphthoyloxy groups; an aralkylcarbonyloxy group such asbenzylcarbonyloxy and 4-t-benzylcarbonyloxy; a (cyclo)acyloxymethylgroup such as acetyloxycarbonylmethyl, propionyloxycarbonylmethyl,butylyloxycarbonylmethyl, cyclohexylcarbonyloxymethyl and4-t-butylcyclohexylcarbonyloxymethyl groups; an arylcarbonyloxymethylgroup such as benzoyloxymethyl and 1-naphthoyloxymethyl; anaralkylcarbonyloxymethyl group such as benzylcarbonyloxymethyl and4-t-butylbenzylcarbonyloxymethyl groups; a 2-(cyclo)acyloxyethyl groupsuch as 2-acetyloxyethyl, 2-propionyloxyethyl, 2-butylyloxyethyl,2-cyclohexylcarbonyloxyethyl and 2-(4-t-butylcyclohexylcarbonyloxy)ethylgroups; a 2-arylcarbonyloxyethyl group such as 2-benzoyloxyethyl and2-(1-naphthoyloxy)ethyl groups; and 2-aralkylcarbonyloxyethyl group suchas 2-benzylcarbonyloxyethyl and 2-(4-t-butylbenzylcarbonyloxy)ethylgroups.

The group —(CH₂)_(i)CN includes, for example, cyano, cyanomethyl,2-cyanoethyl, 2-cyanopropyl, 3-cyanopropyl and 4-cyanobutyl groups.

Further, the halogen atom of A, B, X and Y in the general formulas (1)and general formula (2) includes, for example, F, Cl, Br and I. Themonovalent hydrocarbon group having 1 to 10 carbon atoms of A, B, X andY includes, for example, a (cyclo)alkyl group such as methyl, ethyl,n-propyl, isopropyl, n-butyl, 2-methylpropyl, 1-methylpropyl, t-butyl,n-hexyl, n-octyl, n-decyl, cyclopentyl, cyclohexyl, cycloheptyl andcyclooctyl groups; an aryl group such as phenyl, 4-t-butylphenyl and1-naphthyl groups; and an aralkyl group such as benzyl and4-t-butylbenzyl groups. The monovalent halogenated hydrocarbon grouphaving 1 to 10 carbon atoms of A, B, X and Y includes, for example,halogenated derivatives of said monovalent hydrocarbon group having 1 to10 carbon atoms.

In the resin (A), at least one alicyclic skeleton represented by thegeneral formula (1) and at least one alicyclic skeleton represented bythe general formula (2) can be independently present and the alicyclicskeleton represented by the general formula (1) and the alicyclicskeleton represented by the general formula (2) can be present together.

The resin (A) having an alicyclic skeleton selected from the groupconsisting of the alicyclic skeleton represented by the general formula(1) and the alicyclic skeleton represented by general formula (2), inthe backbone [hereinafter, referred to as “resin (AI)”] can be producedby, for example, the following methods (a) to (e):

(a) A method comprising the step of ring-opening polymerizing orcopolymerizing at least one norbornene derivative represented by thefollowing general formula (7) [hereinafter, referred to as “norbornenederivative (a)”] and optionally at least one other ring-openingcopolymerizable unsaturated alicyclic compound.

wherein in the general formula (7), n, A, B, X and Y each have the samemeaning as in the general formula (1) and general formula (2), R⁵, R⁶,R⁷ and R⁸ represent independently a hydrogen atom, a halogen atom, amonovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalenthalogenated hydrocarbon group having 1 to 10 carbon atoms.

(b) A method comprising radical copolymerizing at least one norbornenederivative (a) and at least one copolymerizable unsaturated compoundsuch as ethylene or maleic acid anhydride.

(c) A method comprising partially hydrolyzing and/or solvolyzing a resinobtained by said method (a) or (b) in accordance with a conventionalprocedure.

(d) A method comprising newly incorporating a group of —COOR¹ or —OCOR²(hereinafter, these groups being together generically referred to as“acid-cleavable ester group”) into the resin obtained by said method (c)by at least partially esterifying the carboxyl groups or hydroxyl groupscontained in said resin in accordance with a conventional procedure.

(e) A method comprising the step of ring-opening (co)polymerizing orradical copolymerizing at least one norbornene derivative [hereinafter,referred to as “norbornene derivative (b)”] represented by the followinggeneral formula (8) and at least partially esterifying the carboxylgroups or hydroxyl groups contained in the resulting (co)polymer inaccordance with a conventional procedure to introduce an acid-cleavableester group into the (co)polymer.

wherein in the general formula (8), n, A and B each have the samemeaning as in the general formula (1) and general formula (2), R⁵, R⁶,R⁷ and R⁸ each have the same meaning as in the general formula (7), Cand D represent independently a hydrogen atom, a halogen atom, amonovalent hydrocarbon group having 1 to 10 carbon atoms, a monovalenthalogenated hydrocarbon group having 1 to 10 carbon atoms,—(CH₂)_(i)COOH or —(CH₂)_(i)OH wherein i has the same meaning as the iin the acid-cleavable group defined in the general formula (1) andgeneral formula (2), provided that at least one of C and D represents—(CH₂)_(i)COOH or —(CH₂)_(i)OH.

Additionally, the resin obtained by said method (c), (d) or (e) can bemodified by, for example, the following method (f):

(f) A method comprising incorporating other acid-cleavable group intosaid resin by further esterifying a carboxyl group or hydroxyl groupcontained in the resin.

The methods (a) to (f) are now described in order.

First, in said method (a), the halogen atom, the monovalent hydrocarbongroup having 1 to 10 carbon atoms and the monovalent halogenatedhydrocarbon group having 1 to 10 carbon atoms, of R⁵, R⁶, R⁷ and R⁸ inthe general formula (7) include, for example, the same groups as thoseexemplified for said general formula (1) and general formula (2).

Among the norbornene derivatives (a), specific examples of the compoundrepresented by the general formula (7) where n is 0 include:

5-methoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-ethoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-n-propoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-isopropoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-n-butoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-(2-methylpropoxy)carbonylbicyclo[2.2.1]hept-2-ene,

5-(1-methylpropoxy)carbonylbicyclo[2.2.1]hept-2-ene,

5-t-butoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-cyclohexyloxycarbonylbicyclo[2.2.1]hept-2-ene,

5-(4′-t-butylcyclohexyloxy)carbonylbicyclo[2.2.1]hept-2-ene,

5-phenoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-tetrahydrofuranyloxycarbonylbicyclo[2.2.1]hept-2-ene,

5-tetrahydropyranyloxycarbonylbicyclo[2.2.1]hept-2-ene,

5-acetyloxybicyclo[2.2.1]hept-2-ene,

5-cyanoyonbicyclo[2.2.1]hept-2-ene,

5-methyl-5-methoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-ethoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-n-propoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-isopropoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-n-butoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-(2-methylpropoxy)carbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-(1-methylpropoxy)carbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-t-butoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-cyclohexyloxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-(4′-t-butylcyclohexyloxy)carbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-phenoxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-tetrahydrofuranyloxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-tetrahydropyranyloxycarbonylbicyclo[2.2.1]hept-2-ene,

5-methyl-5-acetyloxybicyclo[2.2.1]hept-2-ene,

5-methyl-5-cyanobicyclo[2.2.1]hept-2-ene,

5,6-di(methoxycarbonyl)bicyclo[2.2.1]hept-2-ene,

5,6-di(ethoxycarbonyl)bicyclo[2.2.1]hept-2-ene,

5,6-di(n-propoxycarbonyl)bicyclo[2.2.1]hept-2-ene,

5,6-di(isopropoxycarbonyl)bicyclo[2.2.1]hept-2-ene,

5,6-di(n-butoxycarbonyl)bicyclo[2.2.1]hept-2-ene,

5,6-di(t-butoxycarbonyl)bicyclo[2.2.1]hept-2-ene,

5,6-di(phenoxycarbonyl)bicyclo[2.2.1]hept-2-ene,

5,6-di(tetrahydrofuranyloxycarbonyl)bicyclo[2.2.1]hept-2-ene,

5,6-di(tetrahydropyranyloxycarbonyl)bicyclo[2.2.1]hept-2-ene, and

5,6-dicarboxyanhydridebicyclo[2.2.1]hept-2-ene.

Among the norbornene derivatives (a), specific examples of the compoundrepresented by the general formula (7) where n is 1 include:

8-methoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-ethoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-n-propoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-isopropoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-n-butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-(2-methylpropoxy)carbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-(1-methylpropoxy)carbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-t-butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-cyclohexyloxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-(4′-t-butylcyclohexyloxy)carbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-phenoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-tetrahydrofuranyloxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecene,

8-tetrahydropyranyloxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecene,

8-acetyloxytetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-cyanotracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-ethoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-n-propoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-isopropoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-n-butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-(2-methylpropoxy)carbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-(1-methylpropoxy)carbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-t-butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-cyclohexyloxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-(4′-t-butylcyclohexyloxy)carbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-phenoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-tetrahydrofuranyloxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecene,

8-methyl-8-tetrahydropyranyloxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecene,

8-methyl-8-acetyloxytetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-cyanotetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-di(methoxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-di(ethoxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-di(n-propoxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-di(isopropoxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-di(n-butoxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-di(t-butoxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-di(cyclohexyloxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-di(phenoxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-di(tetrahydrofuranyloxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecene,

8,9-di(tetrahydropyranyloxycarbonyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecene,and

8,9-dicarboxyanhydridetetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene.

In the present invention, when two or more of said norbornenederivatives (a) are mixed for use, it is preferred that the compoundrepresented by the general formula (7) where n is 0 and the compoundrepresented by the same formula where n is 1 are used in combination.

Specific examples of the other unsaturated alicyclic compounds capableof ring-opening copolymerizing with the norbornene derivatives (a)include:

bicyclo[2.2.1]hept-2-ene,

bicyclo[2.2.1]hept-2-ene-5-carboxylic acid,

5-methylbicyclo[2.2.1]hept-2-ene-5-carboxylic acid,

5-methylbicyclo[2.2.1]hept-2-ene,

5-ethylbicyclo[2.2.1]hept-2-ene,

tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene-8-carboxylic acid,

8-methyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene-8-carboxylic acid,

8-methyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-ethyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-fluorotetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-fluoromethyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-difluoromethyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-trifluoromethyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene

8-pentafluoroethyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8-difluorotetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-difluorotetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8-bis(trifluoromethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-bis(trifluoromethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-trifluoromethyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8,9-trifluorotetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8,9-tris(trifluoromethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8,9,9-tetrafluorotetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8,9,9-tetrakis(trifluoromethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8-difluoro-9,9-bis(trifluoromethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-difluoro-8,9-bis(trifluoromethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8,9-trifluoro-9-trifluoromethyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8,9-trifluoro-9-trifluoromethoxytetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,8,9-trifluoro-9-pentafluoropropoxytetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-fluoro-8-pentafluoroethyl-9,9-bis(trifluoromethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-difluoro-8-heptafluoroisopropyl-9-trifluoromethyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-chloro-8,9,9-trifluorotetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8,9-dichloro-8,9-bis(trifluoromethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-(2,2,2-trifluorocarboxyethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,

8-methyl-8-(2,2,2-trifluorocarboxyethyl)tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,cyclobutene, cyclopentene, cyclooctene, 1,5-cyclooctadiene,1,5,9-cyclododecatriene, norbornene, 5-ethylidenenorbornene,5-methylnorbornene, dicyclopentadiene,

tricyclo[5.2.1.0^(2,6)]deca-8-ene, tricyclo[5.2.1.0^(2,6)]deca-3-ene,tricyclo[4.4.0.1^(2,5)]undeca-3-ene,

tricyclo[6.2.1.0^(1,8)]undeca-9-ene,tricyclo[6.2.1.0^(1,8)]undeca-4-ene,tetracyclo[4.4.0.1^(2,5).1^(7,10).0^(1,6)]dodec-3-ene,8-methyltetracyclo[4.4.0.1^(2,5).1^(7,10).0^(1,6)]dodec-3-ene,8-ethylidenetetracyclo[4.4.0.1^(2,5).1^(7,12)]dodec-3-ene,8-ethylidenetetracyclo[4.4.0.1^(2,5).1^(7,10).0^(1,6)]dodec-3-ene,pentacyclo[6.5.1.1^(3,6).0^(2,7).0^(9,13)]pentadeca-4-ene, andpentacyclo[7.4.0.1^(2,5).1^(9,12).0^(8,13)]pentadeca-3-ene.

In the resin (AI), the content of the structural units derived from saidother unsaturated alicyclic compound is generally 50 mole % or less,preferably 40 mole % or less, and more preferably 30 mole % or less,based on the total structural units contained in the resin (AI). If thecontent of the structural units derived from the other unsaturatedalicyclic compound is more than 50 mole %, dry etching resistance maytend to lower.

The ring-opening (co)polymerization in the method (a) can be carriedout, for example, using a metathesis catalyst in a suitable solvent.

The metathesis catalyst is comprised of generally a combination of atleast one compound selected from the group consisting of W, Mo and Recompounds (hereinafter, referred to as “specified transition metalcompound”) with at least one compound, selected from the groupconsisting of the compounds of the metals of Group IA, IIA, IIIA, IVAand IVB in the Deming's periodic table, the compounds havingmetal-carbon bonding and/or metal-hydrogen bonding (hereinafter,referred to as “specified organometallic compound”).

The specified transition metal compound includes, for example, halides,oxyhalides, alkoxyhalides, alkoxides, carboxylic acid salts,(oxy)acetylacetonates, carbonyl complexes, acetonitrile complexes,hydride complexes, and their derivatives. Among these compounds,preferred are W compounds or Mo compounds, more specifically halides,oxyhalides or alkoxyhalides of W or of Mo, from the viewpoint ofpolymerization activity, practical use, etc.

The specified transition metal compound may be a compound coordinatedwith a suitable complexing agent such as triphenylphosphine (P(C₆H₅)₃)and pyridine (NC₅H₅).

Specific examples of the specified transition metal compound includeWCl₆, WCl₅, WCl₄, WBr₆, WF₆, WI₆, MoCl₅, MoCl₄, MoCl₃, ReCl₃, WOCl₄,WOCl₃, WOBr₃, MoOCl₃, MoOBr₃, ReOCl₃, ReOBr₃, WCl₂(OC₂H₅)₄, W(OC₂H₅)₆,MoCl₃(OC₂H₅)₂, Mo(OC₂H₅)₅, WO₂(acac)₂ wherein acac stands for anacetylacetonate radical, MoO₂(acac)₂, W(OCOR)₅ wherein OCOR stands for acarboxylic acid radical, Mo(OCOR)₅, W(CO)₆, Mo(CO)₆, Re₂(CO)₁₀,WCl₅.P(C₆H₅)₃, MoCl₅.P(C₆H₅)₃, ReOBr₃.P(C₆H₅)₃, WCl₆.NC₅H₅,W(CO)₅.P(C₆H₅)₃, and W(CO)₃.(CH₃CN)₃.

Among them, particularly preferred are WCl₆, MoCl₅, WCl₂(OC₂H₅)₄ andMOCl₃(OC₂H₅)₂.

Said specified transition metal compound can be used singly or in acombination of two or more thereof.

The specified transition metal compound component constituting ametathesis catalyst can be also used as a mixture of two or morecompounds reacting in a polymerization system to form the specifiedtransition metal compound.

Specific examples of the specified organometallic compound includen-C₄H₉Li, n-C₅H₁₁Na, n-C₆H₅Na, CH₃MgI, C₂H₅MgBr, CH₃MgBr, n-C₃H₇MgCl,t-C₄H₉MgCl, CH₂═CHCH₂MgCl, (C₂H₅)₂Zn, (C₂H₅)₂Cd, CaZn(C₂H₅)₄, (CH₃)₃B,(C₂H₅)₃B, (n-C₄H₉)₃B, (CH₃)₃Al, (CH₃)₂AlCl, CH₃AlCl₂, (CH₃)₃Al₂Cl₃,(C₂H₅)₃Al, (C₂H₅)₃Al₂Cl₃, (C₂H₅)₂Al.O(C₂H₅)₂, (C₂H₅)₂AlCl, C₂H₅AlCl₂,(C₂H₅)₂AlH, (C₂H₅)₂AlOC₂H₅, (C₂H₅)₂AlCN, LiAl(C₂H₅)₂, (n-C₃H₇)₃Al,(i-C₄H₉)₃Al, (i-C₄H₉)₂AlH, (n-C₆H₁₃)₃Al, (n-C₈H₁₇)₃Al, (C₆H₅)₃Al,(CH₃)₄Ga, (CH₃)₄Sn, (n-C₄H₉)₄Sn, (C₂H₅)₃SnH, LiH, NaH, B₂H₆, NaBH₄,AlH₃, LiAlH₄ and TiH₄.

Among these compounds, preferred are (CH₃)₃Al, (CH₃)₂AlCl, CH₃AlCl₂,(CH₃)₃Al₂Cl₃, (C₂H₅)₃Al, (C₂H₅)₂AlCl, C₂H₅AlCl₂, (C₂H₅)₃Al₂Cl₃,(C₂H₅)₂AlH, (C₂H₅)₂AlOC₂H₅, (C₂H₅)₂AlCN, (n-C₃H₇)₃Al, (i-C₄H₉)₃Al,(i-C₄H₉)₂AlH, (n-C₆H₁₃)₃Al, (n-C₈H₁₇)₃Al and (C₆H₅)₃Al.

Said specified organometallic compound can be used singly or in acombination of two or more thereof.

With regard to the quantitative relation between the specifiedtransition metal compound and the specified organometallic compound, thespecified transition metal compound/the specified organometalliccompound is in the range of generally from 1/1 to 1/100, and preferablyfrom 1/2 to 1/50, in terms of metal atomic ratio.

In order to enhance catalytic activity, one or more of the followingactivating agents {circle around (1)} to {circle around (9)} can beadded to said catalyst consisting of a combination of said specifiedtransition metal compound and said specified organometallic compound.

Activating Agent {circle around (1)}:

Boron compounds such as B, BF₃, BCl₃, B(O-n-C₄H₉)₃, BF₃.O(CH₃)₂,BF₃.O(C₂H₅)₂, BF₃.O(n-C₄H₉)₂, BF₃.2C₆H₅OH, BF₃.2CH₃COOH, BF₃.CO(NH₂)₂,BF₃.N(C₂H₄OH)₃, BF₃.piperidine, BF₃.NH₂C₂H₅, B₂O₃ and H₃BO₃; and siliconcompounds such as Si(OC₂H₅)₄ and SiCl₄.

Activating Agent {circle around (2)}:

Alcohols, hydroperoxides, dialkylperoxides and diacylperoxides.

Activating Agent {circle around (3)}:

Water

Activating Agent {circle around (4)}:

Oxygen

Activating Agent {circle around (5)}:

Carbonyl compounds such as aldehydes and ketones; and their oligomers orpolymers.

Activating Agent {circle around (6)}:

Cyclic ethers such as ethylene oxide, epichlorohydrin and oxetane.

Activating Agent {circle around (7)}:

Amides such as N,N-dimethylformamide and N,N-dimethylacetamide; aminessuch as aniline, morpholine and piperidine; and azo compounds such asazobenzene.

Activating Agent {circle around (8)}:

N-Nitroso compounds such as N-nitrosodimethylamine andN-nitrosodiphenylamine.

Activating Agent {circle around (9)}:

Compounds having nitrogen-chlorine bonding or sulfur-chlorine bonding,such as trichloromelamine, N-chlorosuccinimide and phenylsulfenylchloride.

The quantitative relation between these activating agents and thespecified transition metal compound can not be unconditionallydetermined since the relation changes in a very wide variety dependingon the kind of the activating agent to be used. However, in many cases,the activating agent/the specified transition metal compound is in therange of generally from 0.005/1 to 10/1, and preferably from 0.05/1 to3.0/1, in terms of molar ratio.

The average molecular weight of the resin (AI) obtained by thering-opening (co)polymerization in the method (a) can be adjusted bychanging the reaction conditions such as the kind and concentration ofthe metathesis catalyst, the polymerization temperature, the kind andamount of a solvent, and the concentration of a monomer. However, it ispreferred that the average molecular weight is adjusted by adding asuitable molecular weight modifier in a suitable amount to the reactionsystem.

Said molecular weight modifier includes, for example, α-olefins such asethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene,1-nonene and 1-decene; α,ω-diolefins such as 1,3-butadiene and1,4-pentadiene; vinyl aromatic compounds such as styrene andα-methylstyrene; acetylenes; and polar allyl compounds such as allylchloride, allyl acetate and trimethylallyloxysilane.

These molecular weight modifiers can be used singly or in a combinationof two or more thereof.

The amount of the molecular weight modifier used is generally 0.005 to 2moles, preferably 0.02 to 1.0 mole, and more preferably 0.03 to 0.7mole, per mole of the whole monomer.

Further, the solvent used in the method (a) includes, for example,alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane andn-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane,decalin and norbornane; aromatic hydrocarbons such as benzene, toluene,xylene, ethylbenzene and cumene; halogenated hydrocarbons such aschlorobutane, bromohexane, dichloroethane, hexamethylene dibromide andchlorobenzene; and saturated carboxylic acid esters such as ethylacetate, n-butyl acetate, i-butyl acetate and methyl propionate.

These solvents can be used singly or in a combination of two or morethereof.

The radical copolymerization in the method (b) can be carried out, forexample, using a radical polymerization catalyst, such ashydroperoxides, dialkylperoxides, diacylperoxides and azo compounds, ina suitable solvent.

The solvent used in the method (b) includes, for example, thoseexemplified in said method (a) and, in addition thereto, tetrahydrofuranand the like. These solvents can be used singly or in a combination oftwo or more thereof.

The degree of hydrolysis in said method (c) generally ranges from 10 to100 mole %, preferably 20 to 95 mole %.

The degree of introduction of the acid-cleavable ester group accordingto said method (d) generally ranges from 10 to 70 mole %, preferably 20to 60 mole %.

In the method (e), the halogen atom, the monovalent hydrocarbon grouphaving 1 to 10 carbon atoms, and the monovalent halogenated hydrocarbongroup having 1 to 10 carbon atoms, of C and D in the general formula (8)include, for example, the same groups as those exemplified for saidgeneral formula (1) and general formula (2).

The norbornene derivatives (b) include the compounds exemplified forsaid norbornene derivatives (a) in which the ester group therein hasbeen converted into a carboxyl group or a hydroxyl group.

In the present invention, when two or more of said norbornenederivatives (b) are mixed for use, it is also preferred that thecompound represented by the general formula (8) where n is 0 and thecompound represented by the same formula where n is 1 are used incombination.

The (co)polymer used in the method (e) can be obtained by hydrolyzingthe resin (AI) obtained by said method (a) or (b), or may be synthesizedby another method.

The degree of introduction of the acid-cleavable ester group accordingto said method (e) generally ranges from 10 to 70 mole %, preferably 20to 60 mole %.

In said method (f), the other acid-cleavable group includes, forexample, a linear acetal group such as methoxymethyloxy,ethoxymethyloxy, n-propoxymethyloxy, isopropoxymethyloxy,n-butoxymethyloxy, t-butoxymethyloxy, phenoxymethyloxy andtrichloroethoxymethyloxy groups; a cyclic acetal group such astetrahydrofuranyloxy and tetrahydropyranyloxy; a carbonate group such asisopropoxycarbonyloxy, 2-butenyloxycarbonyloxy, t-butoxycarbonyloxy,1-methyl-2-propenyloxycarbonyloxy, cyclohexyloxycarbonyloxy and2-cyclohexenyloxycarbonyloxy groups; an orthocarbonate group such astrimethoxymethyloxy, triethoxymethyloxy, tri-n-propoxymethyloxy andmethoxydiethoxymethyloxy; a (cyclo)alkyl ether such as methyl ether,ethyl ether, n-propyl ether, isopropyl ether, n-butyl ether,2-methylpropyl ether, 1-methylpropyl ether, t-butyl ether, cyclohexylether and t-butylcyclohexyl ether groups; an alkenyl ether such as allylether, 2-butenyl ether, 2-cyclohexenyl ether and 1-methyl-2-propenylether groups; an aralkyl ether such as benzyl ether and t-butyl benzylether groups; and an enol ether such as vinyl ether, 1-propenyl ether,1-butenyl ether, 1,3-butadienyl ether and phenylvinyl ether.

Examples of the introduction reaction of the other acid-cleavable groupaccording to the method (f) include the following:

(f-1) an esterification reaction based on the addition reaction of thecarboxyl group contained in each resin with 2,3-dihydro-4H-pyran,

(f-2) an etherification reaction based on the addition reaction of thehydroxyl group contained in each resin with 2,3-dihydro-4H-pyran, and

(f-3) an esterification reaction based on the reaction of the hydroxylgroup contained in each resin with a dialkyl dicarbonate.

The degree of introduction of the other acid-cleavable group accordingto said method (f) generally ranges from 10 to 70 mole %, preferably 20to 60 mole %.

The resin (A) in the present invention preferably contains a smallamount of carbon-carbon unsaturated bonding from the viewpoint oftransparency to radiation. The resin (A) like this can be obtained, forexample, by effecting addition reaction such as hydrogenation,hydration, addition of a halogen, or addition of a hydrogen halideeither in a suitable step in the ring-opening (co)polymerization methodaccording to said method (a) or said method (e), or after the method (a)or (e). Particularly, the resin (AI) obtained by effecting hydrogenationreaction is preferred. The resin (AI) obtained by said method (b) or theradical (co)polymerization method according to said method (e) hassubstantially no carbon-carbon unsaturated bonding.

The degree of hydrogenation in the hydrogenated resin (AI) is preferably70% or more, more preferably 90% or more, and particularly preferably100%.

The catalysts used in said hydrogenation reaction include those whichhave been used in the conventional hydrogenation reaction of olefiniccompounds.

Among these hydrogenation catalysts, heterogeneous catalysts include,for example, a solid catalyst comprising a noble metal, such as Pd, Pt,Ni, Rh and Ru, supported on a carrier, such as carbon, silica, aluminaand titania. These heterogeneous catalysts can be used singly or incombination of two or more thereof.

On the other hand, homogeneous catalysts include a nickelnaphthenenate/triethylaluminum system, a nickelacetylacetonate/triethylaluminum system, a cobaltoctenoate/n-butyllithium system, a titanocene dichloride/diethylaluminummonochloride system, and a rhodium system such as rhodium acetate andchlorotris(triphenylphosphine)rhodium. These homogeneous catalysts canbe used singly or in combination of two or more thereof.

Among said hydrogenation catalysts, the heterogeneous catalysts arepreferred from the viewpoint of their high reaction activity, their easyremoval after the reaction, and a superior color tone of the resultingresin (AI).

The hydrogenation reaction can be carried out at generally 0 to 200° C.,and preferably 20 to 180° C., in a hydrogen gas atomosphere havinggenerally normal pressure to 300 atm, and preferably 3 to 200 atm.

Preferable resin (AI) in the present invention includes particularly thefollowing resin (AII), resin (AIII) and resin (AIV).

The resin (AII) is a resin comprising a structural unit represented bythe following general formula (3):

wherein in the general formula (3), n is 0 or 1, A represents a hydrogenatom, a halogen atom, a monovalent hydrocarbon group having 1 to 10carbon atoms or a monovalent halogenated hydrocarbon group having 1 to10 carbon atoms, and X represents an acid-cleavable group.

In the general formula (3), the halogen atom, the monovalent hydrocarbongroup having 1 to 10 carbon atoms or the monovalent halogenatedhydrocarbon group having 1 to 10 carbon atoms of A, and theacid-cleavable group of X include, for example, the same groups as thoseexemplified for said general formula (1) and general formula (2).

The resin (AII) preferably contains as the acid-cleavable group of X thegroup —(CH₂)_(i)COOR¹ described as the acid-cleavable group in thegeneral formula (1) and general formula (2), more preferably contains asthe acid-cleavable group of X the group —COOR¹, and particularlypreferably contains as the acid-cleavable group of X a(cyclo)alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl,n-propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl,2-methylpropoxycarbonyl, 1-methylpropoxycarbonyl, t-butoxycarbonyl,n-pentyloxycarbonyl, n-hexyloxycarbonyl, n-heptyloxycarbonyl,n-octyloxycarbonyl, n-decyloxycarbonyl, cyclopentyloxycarbonyl,cyclohexyloxycarbonyl, 4-t-butylcyclohexyloxycarbonyl,cycloheptyloxycarbonyl and cyclooctyloxycarbonyl groups; anaryloxycarbonyl group such as phenoxycarbonyl, 4-t-butylphenoxycarbonyland 1-naphthyloxycarbonyl groups; and an aralkyloxycarbonyl group suchas benzyloxycarbonyl and 4-t-butylbenzyloxycarbonyl.

A more specific typical example of the structural unit of the generalformula (3) is represented by the formula (3-1):

wherein n is 0 or 1, and R¹ is as defined above.

In said resin (AII), one or more structural units represented by thegeneral formula (3) can be present.

The resin (AIII) is a random copolymer comprising a structural unitrepresented by the following general formula (3) and a structural unitrepresented by the following general formula (4).

wherein in the general formula (3) and general formula (4), n and m areindependently 0 or 1, A and B represent independently a hydrogen atom, ahalogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atomsor a monovalent halogenated hydrocarbon group having 1 to 10 carbonatoms, and X represents an acid-cleavable group.

In the general formula (3) and general formula (4), the halogen atom,the monovalent hydrocarbon group having 1 to 10 carbon atoms or themonovalent halogenated hydrocarbon group having 1 to 10 carbon atoms ofA and B, and the acid-cleavable group of X include, for example, thesame groups as those exemplified for said general formula (1) andgeneral formula (2).

The resin (AIII) preferably contains as the acid-cleavable group of Xthe group —(CH₂)_(i)COOR¹ described as the acid-cleavable group in thegeneral formula (1) and general formula (2), more preferably contains asthe acid-cleavable group of X the group —COOR¹, and particularlypreferably contains as the acid-cleavable group of X a(cyclo)alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl,n-propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl,2-methylpropoxycarbonyl, 1-methylpropoxycarbonyl, t-butoxycarbonyl,n-pentyloxycarbonyl, n-hexyloxycarbonyl, n-heptyloxycarbonyl,n-octyloxycarbonyl, n-decyloxycarbonyl, cyclopentyloxycarbonyl,cyclohexyloxycarbonyl, 4-t-butylcyclohexyloxycarbonyl,cycloheptyloxycarbonyl and cyclooctyloxycarbonyl groups; anaryloxycarbonyl group such as phenoxycarbonyl, 4-t-butylphenoxycarbonyland 1-naphthyloxycarbonyl groups; and an aralkyloxycarbonyl group suchas benzyloxycarbonyl and 4-t-butylbenzyloxycarbonyl.

A more specific typical example of the resin (AIII) is comprised of astructural unit of the formula (3-1) above and a structural representedby the formula (4-1):

[Chemical 49]

wherein m is 0 or 1.

The molar ratio of the structural unit represented by the generalformula (3) to the structural unit represented by the general formula(4) in the resin (AIII) is generally 20/80 to 95/5, and preferably 30/70to 90/10.

In the resin (AIII), there can be present one or more structural unitsrepresented by the general formula (3) and one or more structural unitsrepresented by the general formula (4).

The resin (AIV) is a random copolymer containing a structural unitrepresented by the following general formula (5) and a structural unitrepresented by the following general formula (6).

wherein in the general formula (5) and general formula (6), A and Brepresent independently a hydrogen atom, a halogen atom, a monovalenthydrocarbon group having 1 to 10 carbon atoms or a monovalenthalogenated hydrocarbon group having 1 to 10 carbon atoms, and X and Yrepresent independently a hydrogen atom, a halogen atom, a monovalenthydrocarbon group having 1 to 10 carbon atoms, a monovalent halogenatedhydrocarbon group having 1 to 10 carbon atoms or an acid-cleavablegroup, provided that at least one of X and Y is an acid-cleavable group.

In the general formula (5) and general formula (6), the halogen atom,the monovalent hydrocarbon group having 1 to 10 carbon atoms or themonovalent halogenated hydrocarbon group having 1 to 10 carbon atoms ofA, B, X and Y, and the acid-cleavable group of X and Y include, forexample, the same groups as those exemplified for said general formula(1) and general formula (2).

The resin (AIV) preferably contains as the acid-cleavable group of X andY the group —(CH₂)_(i)COOR¹ described as the acid-cleavable group in thegeneral formula (1) and general formula (2), more preferably contains asthe acid-cleavable group of X and Y the group —COOR¹, and particularlypreferably contains as the acid-cleavable group of X and Y a(cyclo)alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl,n-propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl,2-methylpropoxycarbonyl, 1-methylpropoxycarbonyl, t-butoxycarbonyl,n-pentyloxycarbonyl, n-hexyloxycarbonyl, n-heptyloxycarbonyl,n-octyloxycarbonyl, n-decyloxycarbonyl, cyclopentyloxycarbonyl,cyclohexyloxycarbonyl, 4-t-butylcyclohexyloxycarbonyl,cycloheptyloxycarbonyl and cyclooctyloxycarbonyl groups; anaryloxycarbonyl group such as phenoxycarbonyl, 4-t-butylphenoxycarbonyland 1-naphthyloxycarbonyl groups; and an aralkyloxycarbonyl group suchas benzyloxycarbonyl and 4-t-butylbenzyloxycarbonyl.

A more specific typical example of the resin (AIV) is comprised of astructural unit of the formula (5-1) and a structural represented by theformula (6-1):

wherein in the general formula (5-1) and general formula (6-1), R¹ isindependently as defined above.

The molar ratio of the structural unit represented by the generalformula (5) to the structural unit represented by the general formula(6) in the resin (AIV) is generally 5/95 to 95/5, and preferably 10/90to 90/10.

In the resin (AIV), there can be present one or more structural unitsrepresented by the general formula (5) and one or more structural unitsrepresented by the general formula (6).

The resin (A) in the present invention has a weight average molecularweight in terms of polystyrene, measured by gel permeationchromatography (GPC) (hereinafter referred to as “Mw”) of generally5,000 to 300,000, preferably 5,000 to 200,000, and more preferably10,000 to 100,000. If the Mw of the resin is less than 5,000, heatresistance as a photoresist may tend to lower. If the Mw is more than300,000, developability as a photoresist may tend to lower.

The resin (A) in the present invention has a glass transitiontemperature in the range of preferably 80 to 180° C., and morepreferably 90 to 170° C. The glass transition temperature of the resin(A) being in the range of 80 to 180° C. results in obtaining aradiation-sensitive resin composition particularly excellent in heatresistance, sensitivity, etc. as a photoresist.

In the present invention, the resin (A) can be used singly or incombination of two or more thereof.

Further, it is preferred that the resin (A), preferably the resin (AI),and particularly preferably the resin (AII), resin (AIII) and resin(AIV), in the present invention contains impurities in an amount assmall as possible. The impurities result mainly from a catalyst used inthe production of the resins. Examples of the impurities to beconsidered particularly from the view point of a photoresist includehalogens such as fluorine, chlorine and bromine, and the metals of GroupIV, V, VI, VII and VIII in the Deming's periodic table.

It is preferred that the amount of the residual halogen contained in theresin is 3 ppm or less, particularly 2 ppm or less, and that the amountof the residual metal contained is 300 ppb or less, particularly 100 ppbor less. Furthermore, it is preferred that the amount of the residualhalogen contained is 3 ppm or less, particularly 2 ppm or less, and thatthe amount of the residual metal contained is 300 ppb or less,particularly 100 ppb or less. The control of the amounts of theimpurities contained to said values or less results in a furtherimprovement in yield when a semiconductor is produced using theradiation-sensitive resin composition of the present invention as wellas in sensitivity, resolution and process-stability, as a photoresist.

Methods for reducing the impurities contained in the resin, in the caseof the residual halogen, include methods, for example, (a) washing orliquid-liquid extraction of a resin solution with pure water, (b) acombination of washing or liquid-liquid extraction of a resin solutionwith pure water, and a physical purification process such asultrafiltration or centrifugal separation, (c) a method using analkaline aqueous solution or an acidic aqueous solution instead of purewater in the above methods. In case of the residual metal, in additionto the same methods as said methods (a) to (c), (d) a method treating aresin by oxidation, reduction, exchange of ligand, exchange of ion pairor the like to remarkably increase solubility of the residual metalcontained in the resin in a solvent or in water, followed by treatingaccording to said methods (a) to (c).

The treatment for reducing the impurities can be carried out in any stepafter the polymerization step for producing the resin.

(B) Acid-generating Agent

The radiation-sensitive acid-generating agent (hereinafter, referred toas “acid-generating agent (B)”) generating an acid upon irradiation withradiation (hereinafter, referred to as “exposure”) used in the presentinvention has a function of cleaving an acid-cleavable group present inthe resin (A) and/or an acid-cleavable additive as described later bythe action of an acid generated by the exposure, whereby the exposedportion of a photoresist film become readily soluble in an alkalinedeveloping solution and a positive photoresist pattern is formed.

The acid-generating agent (B) includes {circle around (1)} onium salts,{circle around (2)} halongen-containing compounds, {circle around (3)}diazoketone compounds, {circle around (4)} sulfone compounds, and{circle around (5)} sulfonic acid compounds.

Examples of these acid-generating agents (B) include the following.

{circle around (1)} Onium Salts:

Onium salts include, for example, iodonium salts, sulfonium salts,phosphonium salts, diazonium salts and pyridinium salts.

Specific examples of preferable onium salts include diphenyliodoniumtriflate, diphenyliodonium pyrenesulfonate, diphenyliodoniumdodecylbenzenesulfonate, bis(4-t-butylphenyl)iodonium triflate,bis(4-t-butylphenyl)iodonium dodecylbenzenesulfonate,bis(4-t-butylphenyl)iodonium naphthalenesulfonate,bis(4-t-butylphenyl)iodonium hexafluoroantimonate, triphenylsulfoniumtriflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfoniumnaphthalenesulfonate, (hydroxyphenyl)benzenemethylsulfoniumtoluenesulfonate, 1-(naphthylacetomethyl)tetrahydro-thiopheniumtriflate, cyclohexylmethyl(2-oxocyclohexyl)sulfonium triflate,dicyclohexyl(2-oxocyclohexyl)sulfonium triflate,dimethyl(2-oxocyclohexyl)sulfonium triflate,dimethyl(4-hydroxynaphthyl)sulfonium triflate,dimethyl(4-hydroxynaphthyl)sulfonium tosylate,dimethyl(4-hydroxynaphthyl)sulfonium dodecylbenzenesulfonate,dimethyl(4-hydroxynaphthyl)sulfonium naphthalenesulfonate,diphenyliodonium hexafluoroantimonate, triphenylsulfoniumcamphorsulfonate and (4-hydroxyphenyl)benzylmethylsulfoniumtoluenesulfonate.

{circle around (2)} Halongen-containing Compounds:

Halogen-containing compounds include, for example, haloalkylgroup-containing hydrocarbon compounds and, haloalkyl group-containingheterocyclic compounds.

Specific examples of preferable halogen-containing compounds include(trichloromethyl)-s-triazine derivatives such asphenyl-bis(trichloromethyl)-s-triazine,methoxyphenyl-bis(trichloromethyl)-s-triazine andnaphthyl-bis(trichloromethyl)-s-triazine; and1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane.

{circle around (3)} Diazoketone Compounds:

Diazoketone compounds include, for example, 1,3-diketo-2-diazocompounds, diazobenzoquinone compounds and diazonaphthoquinonecompounds.

Specific examples of preferable diazoketones include1,2-naphthoquinonediazide-4-sulfonylchloride,1,2-naphthoquinonediazide-5-sulfonylchloride,1,2-naphthoquinonediazide-4-sulfonic acid ester or1,2-naphthoquinonediazide-5-sulfonic acid ester of2,3,4,4′-tetrahydrobenzophenone, and1,2-naphthoquinonediazide-4-sulfonic acid ester or1,2-naphthoquinonediazide-5-sulfonic acid ester of1,1,1-tris(hydroxyphenyl)ethane.

{circle around (4)} Sulfone Compounds:

Sulfone compounds include, for example, β-ketosulfones,β-sulfonylsulfones, and their α-diazo compounds.

Specific examples of preferable sulfone compounds include 4-trisphenacylsulfone, mesityl phenacyl sulfone and bis(phenylsulfonyl)methane.{circle around (5)} Sulfonic Acid Compounds:

Sulfonic acid compounds include, for example, alkylsulfonic acid esters,alkylsulfonic acid imides, haloalkylsulfonic acid esters, arylsulfonicacid esters and iminosulfonates.

Specific examples of preferable sulfonic acid compounds include benzointosylate, triflate of pyrogallol,nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate,trifluoromethanesulfonylbicyclo[2.2.1]hept-5-ene-2,3-dicarbodiimide,N-hydroxysuccinimide triflate and 1,8-naphthalenedicarboxylic acid imidetriflate.

Among these acid-generating agents (B), particularly preferred arediphenyliodonium triflate, bis(4-t-butylphenyl)iodonium triflate,triphenylsulfonium triflate, cyclohexylmethyl(2-oxocyclohexyl)sulfoniumtriflate, dicyclohexyl(2-oxocyclohexyl)sulfonium triflate,dimethyl(2-oxocyclohexyl)sulfonium triflate,1-(naphthylacetomethyl)tetrahydro-thiophenium triflate,4-hydroxynaphthyl)dimethylsulfonium triflate,dimethyl(4-hydroxynaphthyl)sulfonium triflate,trifluoromethanesulfonylbicyclo[2.2.1]hept-5-ene-2,3-dicarbodiimide,N-hydroxysuccinimide triflate and 1,8-naphthalenedicarboxylic acid imidetriflate.

In the present invention, the acid-generating agent (B) can be usedsingly or in combination of two or more thereof.

The amount of the acid-generating agent (B) used is generally 0.1 to 10parts by weight, preferably 0.5 to 7 parts by weight, per 100 parts byweight of the resin (A), from the viewpoint of ensuring sensitivity anddevelopability as a photoresist. If the amount of the acid-generatingagent (B) used is less than 0.1 part by weight, sensitivity anddevelopability may be lowered. If the amount is more than 10 parts byweight, transparency for radiation is lowered and, as a result, it mayshow a tendency to obtain a rectangular photoresist pattern withdifficulty.

In the case where the resin (A) contains an acid-cleavable group likethe resin (AI), resin (AII), resin (AIII) and resin (AIV), the additionof a compound having a group which is cleavable by the action of an acidto increase affinity of the resin for an alkaline developing solution(hereinafter, referred to as “acid-cleavable additive”) can furtherimprove contrast as a chemically amplified positive type photoresist. Inthe case where the resin (A) used in a radiation-sensitive resincomposition contains no acid-cleavable group, it is necessary to add anacid cleavable additive to the composition so that the composition canbe used as a chemically amplified positive type photoresist.

The acid-cleavable additive includes, for example, polymeric compoundsor low-molecular weight compounds having at least one acid-cleavablegroup such as, for example, hydroxyl group and/or carboxyl groupprotected with t-butyl group, hydroxyl group and/or carboxyl groupprotected with tetrahydropyranyl group, carboxyl group protected with3-oxocyclohexyl group, carboxyl group protected with isobornyl group,hydroxyl group protected with t-butoxycarbonyl group, and the like.

The polymeric compounds out of the acid-cleavable additives include, forexample, polymers and copolymers containing at least one repeated unitselected from the group consisting of t-butyl (meth)acrylate unit,tetrahydropyranyl (meth)acrylate unit, 3-oxocyclohexyl (meth)acrylateunit and isobornyl (meth)acrylate unit.

Specific examples of the polymeric compounds include t-butyl(meth)acrylate homopolymers, t-butyl (meth)acrylate/methyl(meth)acrylate copolymers, t-butyl (meth)acrylate/(meth)acrylic acidcopolymers, t-butyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid copolymers, t-butyl (meth)acrylate/methyl(meth)acrylate/(meth)acrylic acid/adamantyl (meth)acrylate copolymers,t-butyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/adamantylmethyl (meth)acrylate copolymers, t-butyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/tetracyclodekanyl (meth)acrylate copolymers, t-butyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/tetrahydropyranyl (meth)acrylate copolymers, t-butyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/3-oxocyclohexyl(meth)acrylate copolymers, t-butyl (meth)acrylate/methyl(meth)acrylate/(meth)acrylic acid/isobornyl (meth)acrylate copolymers;tetrahydropyranyl (meth)acrylate homopolymers, tetrahydropyranyl(meth)acrylate/methyl (meth)acrylate copolymers, tetrahydropyranyl(meth)acrylate/(meth)acrylic acid copolymers, tetrahydropyranyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid copolymers,tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/adamantyl (meth)acrylate copolymers, tetrahydropyranyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/adamantylmethyl(meth)acrylate copolymers, tetrahydropyranyl (meth)acrylate/methyl(meth)acrylate/(meth)acrylic acid/tetracyclodecanyl (meth)acrylatecopoymers, tetrahydropyranyl (meth)acrylate/methyl(meth)acrylate/(meth)acrylic acid/t-butyl (meth)acrylate copolymers,tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/3-oxocyclohexyl (meth)acrylate copolymers, tetrahydropyranyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/isobornyl(meth)acrylate copolymers; 3-oxocyclohexyl (meth)acrylate homopolymers,3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate copolymers,3-oxocyclohexyl (meth)acrylate/(meth)acrylic acid copolymers,3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acidcopolymers, 3-oxocyclohexyl (meth)acrylate/methyl(meth)acrylate/(meth)acrylic acid/adamantyl (meth)acrylate copolymers,3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/adamantylmethyl (meth)acrylate copolymers, 3-oxocyclohexyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/tetracyclodecanyl (meth)acrylate copoymers, 3-oxocyclohexyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/t-butyl(meth)acrylate copolymers, 3-oxocyclohexyl (meth)acrylate/methyl(meth)acrylate/(meth)acrylic acid/tetrahydropyranyl (meth)acrylatecopolymers, 3-oxocyclohexyl (meth)acrylate/methyl(meth)acrylate/(meth)acrylic acid/isobornyl (meth)acrylate copolymers;isobornyl (meth)acrylate homopolymers, isobornyl (meth)acrylate/methyl(meth)acrylate copolymers, isobornyl (meth)acrylate/(meth)acrylic acidcopolymers, isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid copolymers, isobornyl (meth)acrylate/methyl(meth)acrylate/(meth)acrylic acid/adamantyl (meth)acrylate copolymers,isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/adamantylmethyl (meth)acrylate copolymers, isobornyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/tetracyclodecanyl (meth)acrylate copolymers, isobornyl(meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/t-butyl(meth)acrylate copolymers, isobornyl (meth)acrylate/methyl(meth)acrylate/(meth)acrylic acid/tetrahydropyranyl (meth)acrylatecopolymers, isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylicacid/3-oxocyclohexyl (meth)acrylate copolymers; and the like.

These polymeric compounds can be used singly or as a mixture of two ormore.

Specific examples of the low-molecular weight compounds out of theacid-cleavable additives include t-butyl adamantane-carboxylate,tetrahydropyranyl adamantane-carboxylate, 3-oxocyclohexyladamantane-carboxylate, t-butyl adamantyl acetate, tetrahydropyranyladamantyl acetate, 3-oxocyclohexyl adamantyl acetate; t-butyl1-naphtylacetate, tetrahydropyranyl 1-naphthylacetate, 3-oxocyclohexyl1-naphthylacetate, t-butyl 2-naphthylacetate, tetrahydropyranyl2-naphthylacetate, 3-oxocyclohexyl 2-naphthylacetate, 1-naphthoic acidt-butyl ester, 1-naphthoic acid tetrahydropyranyl ester, 1-naphthoicacid 3-oxocyclohexyl ester, 2-naphthoic acid t-butyl ester, 2-naphthoicacid tetrahydropyranyl ester, 2-naphthoic acid 3-oxocyclohexyl ester;cholic acid t-butyl ester, cholic acid tetrahydropyranyl ester, cholicacid 3-oxocyclohexyl ester; 1-t-butoxycarbonyloxynaphthalene,2-t-butoxycarbonyloxynaphthalene,1,5-bis(t-butoxycarbonyloxy)naphthalene,1-carbo-t-butoxymethoxynaphthalene, 2-carbo-t-butoxymethoxynaphthalene,1,5-bis(carbo-t-butoxymethoxy)naphthalene, and the like.

These low-molecular weight compounds can be used singly or as a mixtureof two or more.

In the present invention, the polymeric compound and the low-molecularweight compound may be used in combination as the acid-cleavableadditive.

The amount of the acid-cleavable additive to be added is normally 200parts by weight or less, preferably 5 to 150 parts by weight, per 100parts by weight of the resin (A). If the amount of the acid-cleavableadditive exceeds 200 parts by weight, adhesion to a substrate may show atendency to drop.

In the positive type radiation-sensitive resin composition of thepresent invention, the addition of a compound which acts as a Lewis baseto an acid generated from the acid-generating agent (B) (hereinafter,referred to as “Lewis base additive”) can improve perpendicularity ofthe side walls of a photoresist patter in section more effectively.

The Lewis base additive includes, for example, nitrogen-containing basiccompounds and salts thereof, carboxylic acids, alcohols, etc. Preferredare the nitrogen-containing basic compounds.

Specific examples of the nitrogen-containing basic compounds includeamine compounds such as triethylamine, tri n-propylamine,triisopropylamine, tri n-butylamine, tri n-hexyl amine, triethanolamine,triphenylamine, aniline, N,N-dimethylaniline, 2-methylaniline,3-methylaniline, 4-methylaniline, 4-nitroaniline, 1-naphthylamine,2-naphthylamine, diphenylamine, ethylenediamine, tetramethylenediamine,hexamethylenediamine, pyrrolidine, piperidine, etc.; imidazole compoundssuch as imidazole, 4-methylimidazole, 4-methyl-2-phenylimidazole,thiabendazole, etc.; pyridine compounds such as pyridine,2-methylpyridine, 4-ethylpyridine, 2-hydroxypyridine, 4-hydroxypyridine,2-phenylpyridine, 4-phenylpyridine, nicotinic acid, nicotinic acidamide, quinoline, acridine, etc.; and other nitrogen-containingheterocyclic compounds such as purine, 1,3,5-triazine,triphenyl-1,3,5-triazine, 1,2,3-triazole, 1,2,4-triazole, and urazol.

These nitrogen-containing basic compounds can be used singly or as amixture of two or more.

The amount of the Lewis base additive to be added is normally 1 mol orless, preferably 0.05 to 1 mole, per mole of the acid-generating agent(B). If the amount of the Lewis base additive exceeds 1 mole,sensitivity as a photoresist of the radiation-sensitive composition mayshow a tendency to drop.

To the radiation-sensitive resin composition of the present inventioncan be added optionally a variety of other additives.

The additives include, for example, surface-active agents acting toimprove coating properties, developability, and so forth.

The surface-active agents include, for example, nonionic surface activeagents such as polyoxyethylene lauryl ether, polyoxyethylene stearylether, polyoxyethylene oleyl ether, polyoxyethylene octyl phenyl ether,polyoxyethylene nonyl phenyl ether, polyethylene glycol dilaurate, andpolyethylene glycol distearate, and the products available under thetradenames of KP341 (products of Shin-Etsu Chemical Co., Ltd.), PolyflowNo. 75 and No. 95 (products of Kyoei-Sha Yushi Kagaku Kogyo K.K.), F-TopEF301, EF303 and EF352 (products of To-chem Products K.K.), MegafacsF171 and F173 (products of Dainippon Ink & Chemicals, Inc.), FluoradFC430 and FC431 (products of Sumitomo 3M Co., Ltd.), and Asahi GuardAG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105 and SC-106(products of Asahi Glass Co., Ltd.).

These surface-active agents can be used singly or as a mixture of two ormore.

The amount of the surface active agent to be added is normally 2 partsby weight or less per 100 parts by weight of the total of the resin (A),the acid-generating agent (B) and the acid-cleavable additive.

Additives other than those described above include a halation preventiveagent, adhesion aid, stabilizer, defoaming agent, etc.

The radiation-sensitive resin composition according to the presentinvention contains as essential components the resin (A) and theacid-generating agent (B), and optionally may contain the acid-cleavableadditive, Lewis base additive, or other additives. The composition isuseful as, particularly, a chemically amplified positive typephotoresist.

In said chemically amplified positive type photoresist, theacid-generating agent (B) generates an acid upon exposure to radiationto produce an acid, and by the action of the acid the acid-cleavablegroup contained in the resin (A) and/or the acid-cleavable additiveundergoes, for example:

(g) a reaction in which an alkoxycarbonyl group cleaves to be convertedinto an carboxyl group,

(h) a reaction in which an alkylcarbonyloxy group cleaves to beconverted into a hydroxyl group,

(i) a reaction in which a cyano group cleaves to be converted into ancarboxyl group,

(j) a reaction in which an acid anhydride group cleaves to be convertedinto carboxyl groups, or the like, so that the exposed portions of thephotoresist become readily soluble in an alkaline developing solutionand are dissolved by the alkaline developing solution and removed awayto give a photoresist pattern of positive type.

Preparation of Composition Solution

The radiation-sensitive resin composition according to the presentinvention is prepared as a composition solution before use by dissolvingthe components in a solvent so that the content of all the solidcomponents may become, for example, 5 to 50% by weight and then normallyfiltering the resulting solution with a filter having a pore diameter ofabout 0.2 μm.

Solvents which can be used for preparation of said composition solutioninclude, for example, n-propyl alcohol, isopropyl alcohol, n-butylalcohol, t-butyl alcohol, cyclohexanol, ethylene glycol monomethylether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propylether, ethylene glycol mono-n-butyl ether, diethylene glycol dimethylether, diethylene glycol diethyl ether, diethylene glycol di-n-propylether, diethylene glycol di-n-butyl ether, ethylene glycol monomethylether acetate, ethylene glycol monoethyl ether acetate, ethylene glycolmono-n-propyl ether acetate, propylene glycol monomethyl ether acetate,propylene glycol monoethyl ether acetate, propylene glycol mono-n-propylether acetate, toluene, xylene, methyl ethyl ketone, methyl n-propylketone, isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone,2-heptanone, 3-heptanone, 4-heptanone, cyclopentanone, cyclohexanone,methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate,methyl 2-hydroxy-3-methylbutyrate, 3-methoxybutyl acetate,3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate,3-methyl-3-methoxybutyl butyrate, ethyl acetate, n-propyl acetate,n-butyl acetate, methyl acetoacetate, ethyl acetate, methyl3-methoxypropionate, ethyl 3-ethoxypropionate, methyl pyruvate, ethylpyruvate, N-methylpyrrolidone, N,N-dimethylformamide,N,N-dimethylacetamide, benzyl ethyl ether, dihexyl ether, diethyleneglycol monomethyl ether, diethylene glycol monoethyl ether,acetonylacetone, isophorone, capric acid, caprylic acid, 1-octanol,1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyloxalate, diethyl maleate, γ-butyrolactone, ethylene carbonate, propylenecarbonate, and so forth.

These solvents can be used singly or as a mixture of two or more.

Method of Forming a Photoresist Pattern

To form a photoresist pattern from the radiation-sensitive resincomposition of the present invention, the composition solution preparedas described above is applied to a substrate such as, for example, asilicon wafer, a wafer covered with aluminum or the like by a suitablecoating method such as spin coating, flow-coating, roll coating or thelike, to form a photoresist film, which is then optionally pre-baked,and thereafter the photoresist film is subjected to exposure so that aprescribed photoresist pattern may be formed. As radiation used inexposure, can be used a variety of radiations, e.g., far ultra-violetradiation such as KrF excimer laser (wave length: 248 nm) or ArF excimerlaser (wave length: 193 nm), X ray such as synchrotron radiation,charged particle radiation such as electron beam, etc. Particularly, KrFexcimer laser or ArF excimer laser is preferred, and ArF excimer laseris more preferred.

In the present invention, it is preferred to carry out heating treatmentafter the exposure (hereinafter, referred to as “post-exposure baking”).The post-exposure baking enables the reactions of (g)-(j) describedabove to proceed smoothly. Although the conditions of heating at thepost-exposure baking vary depending on the formulation of a composition,heating is conducted normally at 30 to 200° C., preferably at 50 to 170°C.

To develop potential performance of the radiation-sensitive resincomposition of the present invention it is possible to form an organicor inorganic anti-reflective coating on a substrate as disclosed in, forexample, Japanese Patent Publication (kokoku) No. 6-12452, or to form aprotective coating on a photoresist film for the purpose of preventinginfluence by basic impurities or the like contained in the environmentalatmosphere as disclosed in, for example, Japanese Laid-open PatentPublication (kokai) No. 5-188598, or to combine these techniques.

Subsequently, the exposed photoresist film is developed, and aprescribed photoresist pattern is thereby formed.

When the radiation-sensitive resin composition of the present inventionis used as a chemically amplified positive type photoresist, developingsolutions which are preferably used include, for example, alkalineaqueous solutions containing at least one alkaline compound such as, forexample, sodium hydroxide, potassium hydroxide, sodium carbonate, sodiumsilicate, sodium metasilicate, aqueous ammonia, ethylamine,n-propylamine, diethylamine, di-n-propylamine, triethylamine,methyldiethylamine, demethylamine, triethanolamine, tetramethylammoniumhydroxide, pyrrole, piperidine, choline,1,8-diazabicyclo[5.4.0]7-undecene, 1,5-diazabicyclo[4.3.0]-5-nonene orthe like. The alkaline aqueous solutions normally have a concentrationof 10% by weight or less. If the concentration exceeds 10% by weight,unexposed portions are also dissolved unfavorably.

To the developing solution of the alkaline aqueous solution, forexample, an organic solvent can be added.

Specific examples of the organic solvent include ketones such asacetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone,cyclohexanone, 3-methyl-2-cyclopentanone, 2,6-dimethylcyclohexanone andthe like; alcohols such as methyl alcohol, ethyl alcohol, n-propylalcohol, isopropyl alcohol, n-butyl alcohol, t-butyl alcohol,cyclopentanol, cyclohexanol, 1,4-hexanediol, 1,4-hexanedimethylol, andthe like; ethers such as tetrahydrofuran, dioxanes and the like; esterssuch as ethyl acetate, butyl acetate, isoamyl acetate and the like;aromatic hydrocarbons such as toluene, xylene and the like; and phenol,acetonylacetone, and dimethylformamide.

These organic solvents can be singly or as a mixture of two or more.

The amount of an organic solvent is preferably 100% by volume or lesswith respect to the alkaline aqueous solution. If the amount of theorganic solvent exceeds 100% by volume, unfavorably developability islowered and serious undeveloped residue is produced at developedportions.

To the developing solution of an alkaline aqueous solution can be addeda surface active agent or the like in a proper amount.

Development with a developing solution of an alkaline aqueous solutionis normally followed by washing with water and drying.

EXAMPLES

Embodiments of the present invention will be described below in greaterdetail by giving Examples. The present invention is by no meansrestricted by these Examples.

In the following Examples other than Example 4 and Comparative Examples,measurement and evaluation were made in the following way.

Mw:

Measured by gel permeation chromatography (GPC) ofmonodisperse-polystyrene standards, using GPC columns G2000HXL (twocolumns), G3000HXL (one column), and G4000HXL (one column), which weremanufactured by Tosoh Co., Ltd., under analysis conditions of a flowrate being 1.0 ml/minute, an elution solvent being tetrahydrofuran and acolumn temperature being 40° C.

Radiation Transmittance:

In respect of a resist film with a dry film thickness of 1.0 μm, formedby spin-coating each resin solution or composition solution on quartzglass, radiation transmittance was calculated from absorbance at awavelength of 248 nm or wavelength of 193 nm, and the values obtainedwere used as measures for transparency in the far-ultraviolet radiationregion.

Etching Rate:

Each resin coat or resist film was subjected to dry etching using a dryetching device (DEM451, manufactured by Nichiden Anelva Co.) underconditions of an etching gas being CF₄, a gas flow rate being 30 sccm, apressure being 5 Pa and a power output being 100 W to measure etchingrate. The lower the etching rate is, the better the dry etchingresistance is.

Adhesion to Substrate:

After development, cleaned positive resist patterns with 0.30 μmline-and-space pairs (1L1S) were examined using a scanning electronmicroscope to observe how the patterns stood adhered. An instance wheredifficulties such as peeling or lifting of patters are not observed isevaluated as “good”; and an instance where such difficulties are seen,as “poor”.

Sensitivity:

Each composition solution was spin-coated on silicone wafers, followedby prebaking for 1 minute on a hot plate kept at 110° C. to form aresist film having a thickness of 0.6 μm. The resist film thus formedwas exposed to light through a mask pattern, using an ArF excimer laserexposure device manufactured by Nikon Corporation (number of lensaperture: 0.50; exposure wavelength: 193 nm). Subsequently, the resistfilm thus exposed was subjected to post-exposure baking for 1 minute ona hot plate kept at 90° C., and thereafter developed at 25° C. for 1minute with an aqueous 2.38% by weight tetramethylammonium hydroxidesolution, followed by washing with water and then drying to form apositive resist pattern. In this processing, the dose of exposure atwhich 0.35 μm line-and-space pairs were formed in a width ratio of 1:1was regarded as an optimum dose of exposure, and this optimum dose ofexposure was indicated as sensitivity.

Resolution:

The size of a minimum positive resist pattern resolved when exposed atthe optimum dose of exposure was indicated as resolution.

Developability:

Positive resist patterns formed in the same manner as in the evaluationof sensitivity were examined using a scanning electron microscope toobserve the degree of scum or undeveloped residue.

Synthesis Example 1

(1) Synthesis of8-Methyl-8-methoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecene:

Into a reaction vessel with an internal volume of 50 liters, having astirrer and kept at a temperature of 180° C. and an internal pressure of3.5 kg/cm².G, methyl methacrylate, dicyclopentadiene and5-methyl-5-methoxycarbonylbicyclo[2.2.1]hept-2-ene were continuously fedat a molar ratio of 1:2.4 (in terms of cyclopentadiene unit): 2.4 bymeans of a constant rate pump while keeping the total feed rate at 4 kgper hour such that the residence time of the reaction materials in thereactor was 8 hours on the average. As a polymerization inhibitor,p-methoxyphenol was dissolved in methyl methacrylate, and the solutionobtained was fed in an amount of 300 ppm (by weight) based on the totalfeed rate of the reaction materials.

During the reaction, the reaction product was drawn out of the reactorat a rate of 4 kg per hour, and continuously fed to a flash distillationcolumn kept at a pressure of 300 Torr and a temperature of 105° C. toseparate a part of unreacted starting materials.

The distillate from the flash distillation column was continuously fedto a distillation column of 3 inches in column diameter, having a V.P.C.packing packed at a height of 119 cm at the enriching section and 102 cmat the recovery section to carry out distillation at a column top(overhead) pressure of 5 Torr and a reflux ratio of 1. Thus, theunreacted starting materials not separable in the flash distillationcolumn were recovered from the column top and a solution containing 67%by weight of8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-enerepresented by the following formula (9) was collected from the columnbottom.

(2) Polymerization:

The inside of a separable flask having a stirrer, a reflux condenser anda three-way cock was replaced with nitrogen, and 100 parts by weight of8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,33 parts by weight of 1-hexene (a molecular weight modifier) and 200parts by weight of toluene were charged into the flask, followed byheating to 80° C. Subsequently, 0.17 part by weight of a toluenesolution of triethylaluminum serving as a metathesis catalyst(concentration: 1.5 mole/liter) and 1.0 part by weight of a toluenesolution of WCl₆ (concentration: 0.05 mole/liter) were added, followedby stirring at 80° C. for 3 hours to effect polymerization to obtain asolution of a resin having a repeating unit represented by the followingformula (yield: 67% by weight). This resin is designated as resin A-1.

(3) Hydrogenation:

In an autoclave, 400 parts by weight of the resin A-1 and as ahydrogenation catalyst 0.075 part by weight ofchlorohydrocarbonyltriphenylphosphine ruthenium were added, followed bytreatment for 4 hours under the conditions of a hydrogen gas pressure of100 kg/cm².G and a temperature of 165° C. to carry out hydrogenationreaction.

Subsequently, 400 parts by weight of the reaction solution obtained and100 parts by weight of toluene were charged into another reactionvessel, and 0.71 part by weight of lactic acid and 1.15 parts by weightof water were added thereto. The mixture obtained was stirred at 60° C.for 30 minutes, followed by adding of 260 parts by weight of methylalcohol, and the mixture obtained was further stirred at 60° C. for 1hour. Thereafter, the reaction vessel was cooled to room temperature toseparate its content into a bad solvent phase (methyl alcohol phase) anda good solvent phase (resin solution phase), and then only the badsolvent phase was drawn out. Thereafter, methyl alcohol corresponding to4.5% by weight of the methyl alcohol drawn out and toluene correspondingto 55% by weight of the same were added in the reaction vessel, followedby stirring at 60° C. for 1 hour. Thereafter, the reaction vessel wasagain cooled to room temperature to separate its content into a badsolvent phase and a good solvent phase, and then only the bad solventphase was drawn out. This operation of extraction with methyl alcoholwas repeated several times. Then, the good solvent phase was separatedand the solvent was evaporated from the good solvent phase to recoverthe resin. Subsequently, the resin obtained was again dissolved intetrahydrofuran, and thereafter again solidified with a large quantityof methyl alcohol. The resin thus solidified was dried under reducedpressure to obtain a purified resin.

This resin had a hydrogenation degree of 100% as measured by NMRspectroscopy, and was a random copolymer having a repeating unitrepresented by the following formula and having an Mw of 15,000. Thisresin is designated as resin AII-1.

(4) Hydrolysis:

Into a flask, 100 parts by weight of the resin AII-1, 200 parts byweight of propylene glycol monoethyl ether, 100 parts by weight ofdistilled water and 10 parts by weight of potassium hydroxide to carryout hydrolysis for 36 hours under reflux in an atmosphere of nitrogen.Subsequently, the reaction solution was cooled and thereafter dropwiseadded in an aqueous solution prepared by dissolving oxalic aciddihydrate in an amount of 1.1 equivalent weight with respect to thesodium hydroxide to solidify the resin.

The resin obtained had a hydrolysis degree of 80% as measured byinfrared spectroscopy and was a random copolymer having repeating unitsrepresented by the following formulas. This resin is designated as resinAIII-1.

(5) Introduction of Protective Group:

Into a flask, 100 parts by weight of the resin AIII-1, 200 parts byweight of dry tetrahydrofuran, 100 parts by weight of dihydropyran and 2parts by weight of pyridinium p-toluenesulfonate were charged, followedby stirring for 36 hours at room temperature in an atmosphere ofnitrogen. Subsequently, 200 parts by weight of ethyl acetate and 400parts by weight of distilled water were added thereto. The mixtureobtained was stirred and thereafter left to stand to separate theorganic layer. This organic layer was washed with water several times,and thereafter the tetrahydrofuran and excess dihydropyran wereevaporated, followed by drying in vacuo to obtain a purified resin.

The resin obtained had a degree of esterification with thetetrahydropyranyl ester group of 95% as measured by infraredspectroscopy and was a random copolymer having repeating unitsrepresented by the following formulas (10-1), (10-2) and (10-3), therepeating units being at a molar ratio of (10-1)/(10-2)/(10-3)=20/4/76;and having an Mw of 18,000. This resin is designated as resin AIII-2.

Synthesis Example 2

(1) Polymerization:

Into the separable flask as used in the step (2) in Synthesis Example 1,and in a stream of nitrogen, 60 parts by weight of5-methyl-5-methoxycarbonylbicyclo[2.2.1]hept-2-ene, 40 parts by weightof8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,25 parts by weight of 1-hexene (a molecular weight modifier), 400 partsby weight of 1,2-dichloroethane, 0.6 part by weight of a chlorobenzenesolution of triethylaluminum serving as a metathesis catalyst(concentration: 1.5 mole/liter) and 4 parts by weight of a chlorobenzenesolution of tungsten hexachloride (concentration: 10.025 mole/liter)were charged to carry out ring-opening copolymerization at 80° C. for 3hours. After the polymerization was completed, a large quantity ofmethanol was added to the polymerization solution to solidify thecopolymer, and the copolymer solidified was separated by filtration,followed by drying in vacuo to obtain a random copolymer havingrepeating units represented by the following formulas (yield: 92% byweight). This copolymer is designated as resin A-2.

(2) Hydrogenation:

In an autoclave, 100 parts by weight of the resin A-2 and, as ahydrogenation catalyst, 10 parts by weight of rhodium supported onactivated carbon (rhodium content: 5% by weight) were added, andthereafter the mixture obtained was dissolved in 2,000 parts by weightof tetrahydrofuran to carry out hydrogenation reaction under 150° C. for5 hours under a hydrogen pressure set at 150 kg/cm². After the reactionwas completed, the hydrogen gas in the reaction vessel was released andalso the hydrogenation catalyst was filtered off from the reactionsolution, followed by adding methanol to solidify hydrogenated resin.Subsequently, this resin was again dissolved in tetrahydrofuran,followed by adding methanol to again solidify the resin. The resin thussolidified was separated by filtration, and then dried in vacuo toobtain a purified resin.

This resin had a hydrogenation degree of 100% as measured by infraredspectroscopy and NMR spectroscopy, and was a random copolymer havingrepeating units represented by the following formulas. This resin isdesignated as resin AIV-1.

(3) Hydrolysis:

In an autoclave, 100 parts by weight of the resin AIV-1 was dissolved in300 parts by weight of tetrahydrofuran, and 10 parts by weight of waterand 10 parts by weight of 85% by weight potassium hydroxide were furtheradded to carry out hydrolysis reaction at 140° C. for 8 hours.Subsequently, the reaction solution was cooled and then 200 parts byweight of an aqueous solution containing 10% by weight oxalic aciddihydrate was added to neutralize the solution, followed by extractingthe resin with 500 parts by weight of methyl isobutyl ketone.Thereafter, the resin solution layer obtained was washed with watertwice, and then poured into n-hexane to solidify the resin. The resinthus solidified was separated by filtration, and then dried in vacuo toobtain a purified resin.

This resin had a hydrolysis degree of 70% as measured by infraredspectroscopy and was a random copolymer having repeating unitsrepresented by the following formulas. This resin is designated as resinAIII-3.

(4) Introduction of Protective Group:

Into a flask, 100 parts by weight of the resin AIII-3 was dissolved in400 parts by weight of ethyl acetate, and 50 parts by weight of3,4-dihydro-2H-pyran and, as a reaction catalyst, 3 parts by weight ofpyridinium p-toluenesulfonate were added to carry out the reaction at25° C. for 8 hours. Subsequently, the operation of adding water and thenseparating the aqueous layer was repeated three times to remove acidcomponents. The resin solution obtained was poured into n-hexane tosolidify the resin. The resin thus solidified was separated byfiltration, and then dried in vacuo to obtain a purified resin.

The resin obtained had a degree of esterification with thetetrahydropyranyloxycarbonyl group (of 85%) as measured by infraredspectroscopy and was a random copolymer having repeating unitsrepresented by the following formulas (11-1) to (11-6), the repeatingunits being at a molar ratio of(11-1)/(11-2)/(11-3)(11-4)/(11-5)/(11-6)=20/6/39/21/11/3; and having anMw of 32,000. This resin is designated as resin AIII-4.

Synthesis Example 3

(1) Polymerization:

Into the separable flask as used in the step (2) in Synthesis Example 2,and in a stream of nitrogen, 70 parts by weight of5-methyl-5-butoxycarbonylbicyclo[2.2.1]hept-2-ene, 30 parts by weight of8,9-dicarboxylic anhydridetetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene, 20 parts by weight of1-hexene (a molecular weight modifier), 400 parts by weight of1,2-dichloroethane, 1.7 parts by weight of an n-hexane solution ofdiethylaluminum chloride serving as a metathesis catalyst(concentration: 10% by weight), 1.8 part by weight of a chlorobenzenesolution of tungsten hexachloride (concentration: 2% by weight) and 0.1parts by weight of a 1,2-dichloroethane solution of para-aldehyde(concentration: 10% by weight) were charged to carry out ring-openingcopolymerization at 60° C. for 7 hours. After the polymerization wascompleted, a large quantity of methanol was added to the polymerizationsolution to solidify the copolymer, and the copolymer solidified wasseparated by filtration, followed by drying in vacuo to obtain a randomcopolymer having repeating units represented by the following formulas(yield: 94% by weight). This copolymer is designated as resin A-3.

(2) Hydrogenation:

The resin A-3 was hydrogenated and purified in the same manner as in thestep (2) of Synthesis Example 2.

This resin had a hydrogenation degree of 100% as measured by infraredspectroscopy and NMR spectroscopy, and was a random copolymer havingrepeating units represented by the following formulas (12-1) and (12-2),the repeating units being at a molar ratio of (12-1)/(12-2)=72/28; andhaving an Mw of 29,000. This resin is designated as resin AII-2.

Synthesis Example 4

(1) Polymerization:

The procedure of the step (1) in Synthesis Example 2 was repeated exceptfor using as monomers 70 parts by weight of5-methyl-5-methoxycarbonylbicyclo[2.2.1]hept-2-ene and 30 parts byweight of 8,9-dicarboxylic anhydridetetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene and, as a molecular weightmodifier, 20 parts by weight of 1-hexene. Thus, a random copolymerhaving repeating units represented by the following formulas (yield: 90%by weight) was obtained. This copolymer is designated as resin A-4.

(2) Hydrogenation:

The resin A-4 was hydrogenated and purified in the same manner as in thestep (2) of Synthesis Example 2.

This resin had a hydrogenation degree of 100% as measured by infraredspectroscopy and NMR spectroscopy, and was a random copolymer havingrepeating units represented by the following formulas and having an Mwof 27,000. This resin is designated as resin AII-3.

(3) Hydrolysis:

In a flask, 100 parts by weight of the resin AII-3 was dissolved in 200parts by weight of tetrahydrofuran, and 100 parts by weight of water wasfurther added to carry out hydrolysis reaction for 12 hours underreflux. Subsequently, the tetrahydrofuran and water were evaporated fromthe reaction solution to obtain a resin.

This resin had a hydrolysis degree of 100% as measured by infraredspectroscopy and was a random copolymer having repeating unitsrepresented by the following formulas. This resin is designated as resinA-5.

(4) Introduction of Protective Group:

Into a flask, 100 parts by weight of the resin A-5 was dissolved in 100parts by weight of ethyl acetate, and 50 parts by weight of3,4-dihydro-2H-pyran and, as a reaction catalyst, 2.5 parts by weight ofpyridinium p-toluenesulfonate were added to carry out the reaction at25° C. for 14 hours. Subsequently, the operation of adding water andthen separating the aqueous layer was repeated three times to removeacid components. The resin solution obtained was poured into n-hexane tosolidify the resin. The resin thus solidified was separated byfiltration, and then dried in vacuo to obtain a purified resin.

The resin obtained had a degree of esterification with thetetrahydropyranyloxycarbonyl group (of 100%) as measured by infraredspectroscopy and was a random copolymer having repeating unitsrepresented by the following formulas (13-1) and (13-2), the repeatingunits being at a molar ratio of (13-1)/(13-2)=22/78; and having an Mw of25,000. This resin is designated as resin AII-4.

Synthesis Example 5

(1) Polymerization:

The procedure of the step (1) in Synthesis Example 2 was repeated exceptfor using as monomers 70 parts by weight of8-methyl-8-t-butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-eneand 30 parts by weight of5-methyl-5-phenoxycarbonylbicyclo[2.2.1]hept-2-ene, and, as a molecularweight modifier, 18 parts by weight of 1-hexene. Thus, a randomcopolymer having repeating units represented by the following formulas(yield: 95% by weight) was obtained. This copolymer is designated asresin A-6.

(2) Hydrogenation:

The resin A-6 was hydrogenated and purified in the same manner as in thestep (2) of Synthesis Example 2.

This resin had a hydrogenation degree of 100% as measured by infraredspectroscopy and NMR spectroscopy, and was a random copolymer havingrepeating units represented by the following formulas. This resin isdesignated as resin AIV-2.

(3) Hydrolysis:

In a flask, 100 parts by weight of the resin AIV-2 was dissolved in 200parts by weight of tetrahydrofuran, and 50 parts by weight of an aqueous2.38% by solution weight of tetramethylammonium hydroxide was furtheradded to carry out hydrolysis reaction for 12 hours under reflux.Subsequently, the reaction solution was cooled and then 15 parts byweight of an aqueous solution containing 10% by weight oxalic aciddihydrate was added to neutralize the solution, followed by extractingthe resin with 400 parts by weight of ethyl acetate. Thereafter, theresin solution layer obtained was washed with water three times, andthen poured into n-hexane to solidify the resin. The resin thussolidified was separated by filtration, and then dried in vacuo toobtain a purified resin.

This resin was confirmed by NMR spectroscopy that its phenoxy carbonylgroups had been quantitatively hydrolyzed, and was a random copolymerhaving repeating units represented by the following formulas (14-1) and(14-2), the repeating units being at a molar ratio of(14-1)/(14-2)=18/82; and having an Mw of 31,000. This resin isdesignated as resin AIII-5.

Synthesis Example 6

(1) Polymerization:

Into the separable flask as used in the step (2) in Synthesis Example 1,and in a stream of nitrogen, 70 parts by weight of5-methyl-5-methoxycarbonylbicyclo[2.2.1]hept-2-ene, 30 parts by weightof 8-ethylidenetetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene, 15 partsby weight of 1-hexene (a molecular weight modifier), 400 parts by weightof 1,2-dichloroethane, 0.6 part by weight of a chlorobenzene solution oftriethylaluminum serving as a metathesis catalyst (concentration: 1.5mole/liter) and 4 parts by weight of a chlorobenzene solution oftungsten hexachloride (concentration: 10.025 mole/liter) were charged tocarry out ring-opening copolymerization at 80° C. for 3 hours. After thepolymerization was completed, a large quantity of methanol was added tothe polymerization solution to solidify the copolymer, and the copolymersolidified was separated by filtration, followed by drying in vacuo toobtain a random copolymer having repeating units represented by thefollowing formulas (yield: 87% by weight). This copolymer is designatedas resin A-7.

(2) Hydrogenation:

The resin A-7 was hydrogenated and purified in the same manner as in thestep (2) of Synthesis Example 2.

This resin had a hydrogenation degree of 100% as measured by infraredspectroscopy and NMR spectroscopy, and was a random copolymer havingrepeating units represented by the following formulas. This resin isdesignated as resin AII-5.

(3) Hydrolysis and Introduction of Protective Group:

The resin AII-5 was hydrolyzed in the same manner as in the step (3) ofSynthesis Example 2 and then esterified in the same manner as in thestep (4) of Synthesis Example 2.

The resin obtained had a degree of esterification with thetetrahydropyranyl group (of 70%) as measured by infrared spectroscopyand was a random copolymer having repeating units represented by thefollowing formulas (15-1) to (15-4), the repeating units being at amolar ratio of (15-1)/(15-2)/(15-3)/(15-4)=21/19/45/15; and having an Mwof 33,000. This resin is designated as resin AIII-6.

Synthesis Example 7

(1) Polymerization:

Into the separable flask as used in the step (1) in Synthesis Example 1,and in a stream of nitrogen, 216 parts by weight of8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,98 parts by weight of maleic anhydride, 16.4 parts by weight ofazobisisobutyronitrile and 157 parts by weight of tetrahydrofuran werecharged to carry out polymerization at 80° C. for 18 hours. After thepolymerization was completed, the reaction solution obtained was pouredinto a large quantity of methanol to solidify the copolymer.Subsequently, the copolymer solidified was again dissolved intetrahydrofuran and then poured into a large quantity of n-hexane toagain solidify the copolymer. The copolymer solidified was separated byfiltration, followed by drying in vacuo to obtain an alternatingcopolymer having a repeating unit represented by the following formula(yield: 55% by weight), and having an Mw of 4,500. This copolymer isdesignated as resin AII-a.

(2) Solvolysis:

In a flask, 100 parts by weight of the resin AII-a was dissolved in 500parts by weight of dry t-butyl alcohol. Thereafter, in an atmosphere ofnitrogen, the reaction was carried out under reflux for 12 hours tothereby solvolyze the anhydride groups in the resin to convert it intoan half ester to obtain an alternating copolymer having a repeating unitrepresented by the following formula and having an Mw of 5,400.

This resin was measured by infrared spectroscopy and NMR spectroscopy toconfirm that the half-esterification reaction had substantiallyquantitatively proceeded. This resin is designated as resin AII-b.

Synthesis Example 8

(1) Synthesis of 5-t-Butoxycarbonylbicyclo[2.2.1]hept-2-ene and8-t-Butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene:

Into an autoclave with an internal volume of 2 liters, 256.3 g oft-butyl acrylate, 264.4 g of dicyclopentadiene and 1,040 g of toluenewere charged, and the reaction was carried out at a temperature of 170°C. or higher for 5 hours. Subsequently, the reaction product was drawnout, and the toluene was evaporated, followed by distillation using adistillation column at 8.0 Torr and 87° C. to obtain 250 g of5-t-butoxycarbonylbicyclo[2.2.1]hept-2-ene with a purity of 99.9% byweight. Using the same distillation column, the product was distilled at0.07 Torr and 97 to 102° C. to obtain 100 g of8-t-butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene with apurity of 99.9% by weight:

(2) Polymerization:

Into the separable flask as used in the step (2) in Synthesis Example 1,and in a stream of nitrogen, 40 parts by weight of5-t-butoxycarbonylbicyclo[2.2.1]hept-2-ene, 26 parts by weight of1-hexene (a molecular weight modifier) and 80 parts by weight of toluenewere charged, followed by heating to 80° C. Subsequently, 5.14 parts byweight of a toluene solution of triethylaluminum serving as a metathesiscatalyst (concentration: 0.123 mole/liter) and 3.4 parts by weight of atoluene solution of WCl₆ (concentration: 0.025 mole/liter) were added,followed by stirring at 80° C. for 3 hours to effect polymerization toobtain a solution of a resin having a repeating unit represented by thefollowing formula (yield: 60% by weight). This resin is designated asresin A-10.

(3) Hydrogenation:

The resin A-10 was hydrogenated and purified in the same manner as inthe step (3) of Synthesis Example 1 to obtain a resin having ahydrogenation degree of 100% as measured by NMR spectroscopy, having arepeating unit represented by the following formula and having an Mw of42,000. This resin is designated as resin AII-6.

(4) Cut-down of Impurities:

A toluene solution of the resin AII-6 was mixed with an aqueous solutionof 5% by weight triethanolamine. The mixture obtained was stirred at 70°C. for 12 hours, and then left to stand to effect separation to removethe aqueous layer. This operation was repeated 10 times, followed bywashing with water three times. Subsequently, the resin was againsolidified with methyl alcohol, and the resin solidified was filtered,and then dried. This resin is designated as resin AII-6a.

The resin AII-6a had residual tungsten, residual aluminum and residualruthenium in a content not more than 250 ppb each, and residual chlorinenot more than 50 ppb. On the other hand, the resin AII-6 had residualtungsten in a content of 6 ppm, and residual chlorine in a content of 10ppm.

To determine the content of the residual metals in the resin AII-6a andresin AII-6, each resin was baked using a muffle furnace to effectashing, and then the metals were determined using an inducibly coupledplasma emission spectroscopic analyzer SPS7700, manufactured by SeikoDenshi Kogyo K.K. To determine the content of the residual chlorine, afilm of each resin was formed on an aluminum plate, and the chlorine wasdetermined using a fluorescent X-ray analyzer Model PW1404, manufacturedby Philips Co.

(5) Hydrolysis:

Into a flask, 100 parts by weight of the resin AII-6a, 200 parts byweight of propylene glycol monoethyl ether and 10 parts by weight of 20%by weight sulfuric acid were charged to carry out hydrolysis for 8 hoursunder reflux in an atmosphere of nitrogen. Subsequently, the reactionsolution was cooled, and thereafter 200 parts by weight of water and 200parts by weight of ethyl acetate were added to carry out extractionoperation. Thereafter, the resin layer obtained was washed with waterthree times, and then dropwise added in a large quantity of n-hexane toagain solidify the resin. The resin solidified was dried under reducedpressure.

The resin thus obtained was measured by infrared spectroscopy to confirmthat the hydrolysis reaction quantitatively proceeded, and was a resinhaving a repeating unit represented by the following formula. This resinis designated as resin A-11.

(6) Introduction of Protective Group:

Into a flask, 100 parts by weight of the resin AII, 200 parts by weightof dry tetrahydrofuran, 100 parts by weight of dihydropyran and 2 partsby weight of pyridinium p-toluenesulfonate were charged, followed bystirring for 36 hours at room temperature in an atmosphere of nitrogen.Subsequently, 200 parts by weight of ethyl acetate and 400 parts byweight of distilled water were added thereto. The mixture obtained wasstirred and thereafter left to stand to separate the organic layer. Thisorganic layer was washed with water several times, and thereafter thetetrahydrofuran and excess dihydropyran were evaporated, followed bydrying in vacuo to obtain a purified resin.

The resin obtained had a degree of esterification with thetetrahydropyranyl ester group (of 98%) as measured by infraredspectroscopy and was a random copolymer having repeating unitsrepresented by the following formulas (16-1) and (16-2), the repeatingunits being at a molar ratio of (16-1)/(16-2)=2/98; and having an Mw of25,000 and a glass transition point of 95° C. This resin is designatedas resin AIII-7.

Synthesis Example 9

(1) Polymerization:

Into the separable flask as used in the step (2) in Synthesis Example 1,and in a stream of nitrogen, 60 parts by weight of5-t-butoxycarbonylbicyclo[2.2.1]hept-2-ene and 20 parts by weight of8-t-butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,obtained in the step (1) in Synthesis Example 8, 12 parts by weight of1-hexene (a molecular weight modifier) and 160 parts by weight oftoluene were charged, followed by heating to 80° C. Subsequently, 15parts by weight of a toluene solution of triethylaluminum serving as ametathesis catalyst (concentration: 0.123 mole/liter) and 9.3 parts byweight of a toluene solution of WCl₆ (concentration: 0.025 mole/liter)were added, followed by stirring at 80° C. for 3 hours to effectpolymerization to obtain a solution of a random copolymer havingrepeating units represented by the following formulas (yield: 50% byweight). This resin is designated as resin A-12.

(2) Hydrogenation:

The resin A-12 was hydrogenated and purified in the same manner as inthe step (3) of Synthesis Example 1 to obtain a random copolymer havinga hydrogenation degree of 100% as measured by NMR spectroscopy, havingrepeating units represented by the following formulas and having an Mwof 34,000. This resin is designated as resin AIV-3.

(3) Hydrolysis:

Into a flask, 100 parts by weight of the resin AIV-3, 200 parts byweight of propylene glycol monoethyl ether and 10 parts by weight of 20%by weight sulfuric acid were charged to carry out hydrolysis for 8 hoursunder reflux in an atmosphere of nitrogen. Subsequently, the reactionsolution was cooled, and thereafter 200 parts by weight of water and 200parts by weight of ethyl acetate were added to carry out extraction.Thereafter, the resin layer obtained was washed with water three times,and then dropwise added in a large quantity of n-hexane to againsolidify the resin. The resin solidified was dried under reducedpressure.

The resin thus obtained was measured by infrared spectroscopy to confirmthat the hydrolysis reaction quantitatively proceeded, and was a randomcopolymer having repeating units represented by the following formulas.This resin is designated as resin A-13.

(4) Introduction of Protective Group:

Into a flask, 100 parts by weight of the resin A-13, 200 parts by weightof dry tetrahydrofuran, 100 parts by weight of dihydropyran and 2 partsby weight of pyridinium p-toluenesulfonate were charged, followed bystirring for 48 hours at 30° C. in an atmosphere of nitrogen.Subsequently, 200 parts by weight of ethyl acetate and 400 parts byweight of distilled water were added thereto. The mixture obtained wasstirred and thereafter left to stand to separate the organic layer. Thisorganic layer was washed with water several times, and thereafter thetetrahydrofuran and excess dihydropyran were evaporated, followed bydrying in vacuo to obtain a purified resin.

The resin obtained had a degree of esterification with thetetrahydropyranyl ester group (of 97%) as measured by infraredspectroscopy and was a random copolymer having repeating unitsrepresented by the following formulas (17-1) to (17-4), the repeatingunits being at a molar ratio of (17-1)/(17-2)/(17-3)/(17-4)=1/2/81/16;and having an Mw of 32,000. This resin is designated as resin AIII-8.

Synthesis Example 10

(1) Polymerization:

Into the separable flask as used in the step (2) in Synthesis Example 1,and in a stream of nitrogen, 34.3 parts by weight of5-t-butoxycarbonylbicyclo[2.2.1]hept-2-ene and 45.7 parts by weight of8-t-butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,obtained in the step (1) in Synthesis Example 8, 22 parts by weight of1-hexene (a molecular weight modifier) and 160 parts by weight oftoluene were charged, followed by heating to 80° C. Subsequently, 4parts by weight of a toluene solution of triethylaluminum serving as ametathesis catalyst (concentration: 0.575 mole/liter) and 11.4 parts byweight of a toluene solution of WCl₆ (concentration: 0.025 mole/liter)were added, followed by stirring at 80° C. for 3 hours to effectpolymerization to obtain a solution of a random copolymer havingrepeating units represented by the following formulas (yield: 65% byweight). This resin is designated as resin A-14.

(2) Hydrogenation:

The resin A-14 was hydrogenated and purified in the same manner as inthe step (3) of Synthesis Example 1 to obtain a random copolymer havinga hydrogenation degree of 100% as measured by NMR spectroscopy, havingrepeating units represented by the following formulas and having an Mwof 28,000. This resin is designated as resin AIV-4.

(3) Hydrolysis:

Into a flask, 100 parts by weight of the resin AIV-4, 200 parts byweight of propylene glycol monoethyl ether and 10 parts by weight of 20%by weight sulfuric acid were charged to carry out hydrolysis for 8 hoursunder reflux in an atmosphere of nitrogen. Subsequently, the reactionsolution was cooled, and thereafter 200 parts by weight of water and 200parts by weight of ethyl acetate were added to carry out extraction.Thereafter, the resin layer obtained was washed with water three times,and then dropwise added in a large quantity of n-hexane to againsolidify the resin. The resin solidified was dried under reducedpressure.

The resin thus obtained was measured by infrared spectroscopy to confirmthat the hydrolysis reaction quantitatively proceeded, and was a randomcopolymer having repeating units represented by the following formulas.This resin is designated as resin A-15.

(4) Introduction of Protective Group:

Into a flask, 100 parts by weight of the resin A-15, 200 parts by weightof dry tetrahydrofuran, 100 parts by weight of dihydropyran and 2 partsby weight of pyridinium p-toluenesulfonate were charged, followed bystirring for 48 hours at 30° C. in an atmosphere of nitrogen.Subsequently, 200 parts by weight of ethyl acetate and 400 parts byweight of distilled water were added thereto. The mixture obtained wasstirred and thereafter left to stand to separate the organic layer. Thisorganic layer was washed with water several times, and thereafter thetetrahydrofuran and excess dihydropyran were evaporated, followed bydrying in vacuo to obtain a purified resin.

The resin obtained had a degree of esterification with thetetrahydropyranyl ester group (of 98%) as measured by infraredspectroscopy and was a random copolymer having repeating unitsrepresented by the following formulas (18-1) to (18-4), the repeatingunits being at a molar ratio of (18-1)/(18-2)/(18-3)/(18-4)=1/1/49/49;and having an Mw of 27,000. This resin is designated as resin AIII-9.

Synthesis Example 11

(1) Polymerization:

Into the separable flask as used in the step (2) in Synthesis Example 1,and in a stream of nitrogen, 40 parts by weight of5-t-butoxycarbonylbicyclo[2.2.1]hept-2-ene and 20 parts by weight of8-t-butoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene,obtained in the step (1) in Synthesis Example 8, 20 parts by weight of5-methyl-5-methoxycarbonylbicyclo[2.2.1]hept-2-ene, 24 parts by weightof 1-hexene (a molecular weight modifier) and 160 parts by weight oftoluene were charged, followed by heating to 80° C. Subsequently, 15parts by weight of a toluene solution of triethylaluminum serving as ametathesis catalyst (concentration: 0.123 mole/liter) and 9.3 parts byweight of a toluene solution of WCl₆ (concentration: 0.025 mole/liter)were added, followed by stirring at 80° C. for 3 hours to effectpolymerization to obtain a solution of a random copolymer havingrepeating units represented by the following formulas (yield: 70% byweight). This resin is designated as resin A-16.

(2) Hydrogenation:

The resin A-16 was hydrogenated and purified in the same manner as inthe step (3) of Synthesis Example 1 to obtain a random copolymer havinga hydrogenation degree of 100% as measured by NMR spectroscopy andhaving repeating units represented by the following formulas. This resinis designated as resin AIV-5.

(3) Hydrolysis:

Into a flask, 100 parts by weight of the resin AIV-5, 200 parts byweight of propylene glycol monoethyl ether and 10 parts by weight of 20%by weight sulfuric acid were charged to carry out hydrolysis for 8 hoursunder reflux in an atmosphere of nitrogen. Subsequently, the reactionsolution was cooled, and thereafter 200 parts by weight of water and 200parts by weight of ethyl acetate were added to carry out extraction.Thereafter, the resin layer obtained was washed with water three times,and then dropwise added in a large quantity of n-hexane to againsolidify the resin. The resin solidified was dried under reducedpressure.

The resin thus obtained was measured by infrared spectroscopy to confirmthat the hydrolysis reaction quantitatively proceeded, and was a randomcopolymer having repeating units represented by the following formulas(19-1) to (19-3), the repeating units being at a molar ratio of(19-1)/(19-2)/(19-3)=33/52/15; and having an Mw of 32,000. This resin isdesignated as resin AIII-10.

Synthesis Example 12

(Acid-cleavable Additive)

In a reactor were charged 10 parts by weight of 1,5-dihydronaphthalene,29.2 parts by weight of di-t-butyl dicarbonate, 13.9 parts by weight oftriethylamine and 100 parts by weight of dioxane, and they are heated to70° C. to react for 5 hours. After the completion of the reaction,dioxane was distilled off, and then the residual matter was dissolved inethyl acetate, washed with 5% by weight aqueous potassium hydroxidesolution, and further washed with water twice. The resulting ethylacetate solution was dehydrated with magnesium sulfate. From thedehydrated solution thus obtained,1,5-bis(t-butoxycarbonyloxy)naphthalene having the structural formulabelow in a white crystalline state. The compound is referred to as C-2.

Example 1

A resin film formed using a tetrahydrofuran solution of the resin AII-1obtained in Synthesis Example 1 was examined by measuring its radiationtransmittance and etching rate. Results of the measurement are shown inTable 1.

Example 2

A resin film formed using a tetrahydrofuran solution of the resin AIII-2obtained in Synthesis Example 1 was examined by measuring its radiationtransmittance and etching rate. Results of the measurement are shown inTable 1.

Example 3

Using azoisobutyronitrile as a polymerization initiator andt-dodecylmercaptan as a chain transfer agent, a t-butyl methacrylate,methyl methacrylate and methacrylic acid were polymerized to obtain acopolymer having a t-butyl methacrylate/methyl methacrylate/methacrylicacid compositional ratio of 40/50/10 and an Mw of 25,000. This copolymeris designated as acid-cleavable additive C1.

Subsequently, 50 parts by weight of the resin AIII-2, 50 parts by weightof the acid-cleavable additive C1 and 5 parts by weight oftriphenylsulfonium trifurate (an acid-generating agent B1) weredissolved in a 80:20 (weight ratio) mixed solvent of 2-heptanone andethyl 2-hydroxypropionate to prepare a composition solution. Thissolution is designated as composition solution α.

A resist film formed using the composition solution α was examined bymeasuring its radiation transmittance and etching rate. Results of themeasurement are shown in Table 1.

Comparative Example 1

A resin film formed using a solution prepared by dissolving in ethyl2-hydroxypropionate the acid-cleavable additive C1 obtained in Example 3was examined by measuring its etching rate. Results of the measurementare shown in Table 1.

Comparative Example 2

100 parts by weight of cresol novolak resin with an Mw of 5,000 and 25parts by weight of 1,2-quinonediazido-5-sulfonate of2,3,4,4′-tetrahydroxybenzophenone (an acid-generating agent B2) weredissolved in ethyl 2-hydroxypropionate to prepare a compositionsolution. This solution is designated as composition solution β1.

A resist film formed using the composition solution β1 was examined bymeasuring its radiation transmittance. Results of the measurement areshown in Table 1.

TABLE 1 Acid- Acid- Radiation generat- cleav- transmittance Etching ingable (%) rate Resin agent (B) additive 248 mm 193 mm (Å/min) Example 1AII-1 — — 98.8 81.2 195 Example 2 AIII-2 — — 98.8 74.2 220 Example 3AIII-2 B1 C1 98.9 78.2 188 Comparative — — C1 — — 410 Example 1Comparative Cresol- B2 — 25.2 0.02 — Example 2 novolak resin

Example 4

10 g of the composition solution β1 obtained in Comparative Example 2was further diluted with 20 g of ethyl 2-hydroxypropionate to prepare acomposition solution, designated as composition solution β2. Thesolution obtained was coated on a silicon substrate, followed by bakingat a temperature of 300° C. to form a film with a layer thickness of 0.1μm.

On the film thus formed, the composition solution a obtained in Example3 was coated, followed by baking to form a resist film with a layerthickness of 0.6 μm. Thereafter, on this resist film, an aqueoussolution of polyacrylic acid was coated to form an upper layer film.

Subsequently, the triple-layer film thus obtained was exposed to lightusing a KrF excimer laser stepper (NSR-2005 EX8A, manufactured by NikonCorporation; numerical aperture: 0.50), followed by post-exposurebaking. Thereafter, the film exposed was developed using an aqueoussolution of 2.38% by weight of tetramethylammonium hydroxide, followedby washing with pure water and then drying. As a result, a positiveline-and-space pattern with a line width of 0.3 μm was obtained in agood rectangular shape.

Examples 5 to 11

The resin AIII-4, AII-2, AII-4, AIII-5, AIII-6 or AII-b, which wasobtained in one of synthesis Examples 2 to 7, was mixed with thefollowing acid-generating agent B, Lewis base additive and solvent toform a uniform solution, followed by filtration with a membrane filterhaving a pore diameter of 0.2 μm. Thus, composition solutions as shownin Table 2 were prepared (in the table, “part(s)” is by weight).

Using the respective composition solutions thus obtained, positiveresist patterns were formed under the developing conditions of adevelopment time of 1 minute using an aqueous 2.38% by weighttetramethylammonium hydroxide solution [developing condition (i)] or adevelopment time of 1 minute using an aqueous 0.238% by weighttetramethylammonium hydroxide solution [developing condition (ii)], andthen each evaluation was made. Results of the evaluation are shown inTable 3.

Acid-generating Agent B

B3: Cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifurate

B4: 4-Hydroxynaphthyldiemthylsulfonium trifurate

B5: Trifluoromethanesulfonylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide

Lewis Base Additive

D1: Tri-n-butylamine

D2: 2-Hydroxypyridine

Solvent

E1: Ethyl 2-hydroxypropionate

E2: n-Butyl acetate

E3: 2-Heptanone

TABLE 2 Acid- Lewis Resin generating base Solvent (A) (Parts) agent (B)(Parts) additive (Parts) (parts) Example 5 AIII-4 (100) B4 (2.5) D1(0.03) E1/E3 (173/406) Example 6 AII-2 (100) B3 (2.5) D2 (0.03) E3 (580)Example 7 AII-4 (100) B4 (2.5) D1 (0.03) E3 (580) Example 8 AII-4 (100)B4 (2.5) D1 (0.03) E2/E3 (173/406) Example 9 AIII-5 (100) B5 (2.5) D2(0.03) E1/E3 (173/406) Example 10 AIII-6 (100) B4 (2.5) D1 (0.01) E1/E3(173/406) Example 11 AII-b (100) B4 (2.5) D1 (0.01) E1(420)

TABLE 3 Devel- Radiation Adhe- Sensi- Res- oping Radition sion to tivityolu- De- condi- transmittance sub- (mJ/ tion velop- tions (193 nm; %)strate cm²) (μm) ability Example 5 (ii) 63 good 17 0.22 good Example 6(i) 68 good 18 0.22 good Example 7 (i) 71 good 22 0.22 good Example 8(ii) 62 good 15 0.24 good Example 9 (i) 61 good 08 0.22 good Example 10(i) 65 good 23 0.20 good Example 11 (ii) 65 good 35 0.25 good

Examples 12 to 17

The resin AIII-7, A11, A13, AIII-8, AIII-9 or AIII-10, which wasobtained in one of synthesis Examples 8 to 11, was mixed with theaforesaid acid-generating agent B4, Lewis base additive D1 and solventE3 to form a uniform solution, followed by filtration with a membranefilter having a pore diameter of 0.2 μm. Thus, composition solutions asshown in Table 4 were prepared (in the table, “part(s)” is by weight).

Using the respective composition solutions thus obtained, positiveresist patterns were formed in the same manner as in Example 4 exceptfor using a KrF excimer laser exposure device (manufactured by NikonCorporation; number of lens aperture: 0.55), and then each evaluationwas made. Results of the evaluation are shown in Table 5.

The resist pattern obtained in Example 12 was heated to 90° C. on a hotplate to examine how the pattern deformed. As a result, no change wasobserved at all, also showing a good heat resistance.

TABLE 4 Acid- gener- Lewis Sol- Resin ating a- base vent (A) (Parts)gent (B) (Parts) additive (Parts) (parts) Exam- AIII-7 (100) B4 (2.5) D1(0.01) E3 ple 12 (500) Exam- AIII-7 (70) B4 (2.5) D1 (0.01) E3 ple 13A-11 (30) (500) Exam- AIII-8 (100) B4 (2.5) D1 (0.01) E3 ple 14 (500)Exam- AIII-8 (50) B4 (2.5) D1 (0.01) E3 ple 15 A-13 (50) (500) Exam-AIII-9 (100) B4 (2.5) D1 (0.01) E3 ple 16 (500) Exam- AIII-9 (50) B4(2.5) D1 (0.01) E3 ple 17 AIII-10 (50) (500) Exam- AII-6a (100) B4 (2.5)D1 (0.01) E3 ple 18 (500)

TABLE 5 Devel- Radiation Adhe- Sensi- Res- oping trans- sion to tivityolu- De- condi- mittance sub- (mJ/ tion velop- tions (193 nm; %) stratecm²) (μm) ability Example 12 (i) 64 good 26 0.22 good Example 13 (i) 65good 32 0.20 good Example 14 (i) 66 good 20 0.22 good Example 15 (i) 64good 25 0.18 good Example 16 (i) 65 good 29 0.18 good Example 17 (i) 63good 33 0.18 good Example 18 (i) 73 good 17 0.18 good

Example 19

80 parts by weight of the resin (AIII-3) obtained in Synthesis Example2(3), 20 parts weight of the acid-cleavable additive (C-2) obtained inSynthesis Example 12, 1.5 parts by weight of (B-4) and 1.5 parts byweight of (B-3) as an acid-generating agent, 0.02 part by weight of theLewis base additive (D-1) and 500 parts by weight of the solvent (E1)were mixed to produce a uniform solution, followed by filtration with amembrane filter having a pore diameter of 0.2 μm. Thus, a compositionsolution was prepared.

Using the composition solution thus obtained, a positive resist patternwase formed in the same manner as in Example 5 except for using a ArFexcimer laser exposure device (manufactured by Nikon K.K.; number oflens aperture: 0.55), and then each evaluation was made. Results of theevaluation are shown in Table 6.

TABLE 6 Radiation Sensi- trans- Adhesion tivity Resolu- mittance to (mJ/tion Develop- (193; nm %) substrate cm²) (μm) ability Example 19 59 good37 0.20 good

What is claimed is:
 1. A copolymer comprising a structure having theformula (I):

wherein n is 0 or 1, A and B represent independently a hydrogen atom, ahalogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atomsor a monovalent halogenated hydrocarbon group having 1 to 10 carbonatoms, and X and Y represent independently a hydrogen atom, a halogenatom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, amonovalent halogenated hydrocarbon group having 1 to 10 carbon atoms oran acid-cleavable group, provided that at least one of X and Y is anacid-cleavable group, or X and Y are bonded to each other to form abivalent group represented by the formula:

wherein Z is —O— or —N(R³)— in which R³ is a hydrogen atom, a halogenatom, an alkyl group having 1 to 8 carbon atoms or a —SO₂R⁴ group having1 to 4 carbon atoms in which R⁴ is an alkyl group having 1 to 4 carbonatoms or a halogenated alkyl group having 1 to 4 carbon atoms, or theformula: —O—.
 2. The copolymer according to claim 1, wherein theacid-cleavable group is a group: —(CH₂)_(i)COOR¹, —(CH₂)_(i)OCOR² or—(CH₂)_(i)CN wherein R¹ is a hydrocarbon group having 1 to 10 carbonatoms, a halogenated hydrocarbon group having 1 to 10 carbon atoms, atetrahydrofuranyl group, a tetrahydropyranyl group, a carbobutoxymethylgroup, a carbobutoxyethyl group, a carbobutoxypropyl group or atrialkylsilyl group the alkyl groups of which each have 1 to 4 carbonatoms, R² represents a hydrocarbon group having 1 to 10 carbon atoms ora halogenated hydrocarbon group having 1 to 10 carbon atoms, and i is aninteger of 0 to
 4. 3. The copolymer according to claim 2, wherein theacid-cleavable group is an alkoxycarbonyl group or a cycloalkoxycarbonylgroup.
 4. The copolymer according to claim 3, wherein the acid-cleavablegroup is a methoxycarbonyl, ethoxycarbonyl, n-butoxycarbonyl,t-butoxycarbonyl or cyclohexyloxycarbonyl group.
 5. The copolymeraccording to claim 1, wherein said structure is represented by theformula (II):

wherein R⁵ is a hydrocarbon group having 1 to 10 carbon atoms, ahalogenated hydrocarbon group having 1 to 10 carbon atoms, atetrahydrofuranyl group, a tetrahydropyranyl group, a carbobutoxymethylgroup, a carbobutoxyethyl group, a carbobutoxypropyl group or atrialkylsilyl group, the alkyl groups of which each have 1 to 4 carbonatoms.
 6. The copolymer according to claim 5, wherein the R⁵ in thegeneral formula (II) is a methyl, ethyl, n-butyl, t-butyl or cyclohexylgroup.
 7. A radiation-sensitive resin composition comprising: (A) acopolymer comprising a structure having the general formula (I):

wherein n is 0 or 1, A and B represent independently a hydrogen atom, ahalogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atomsor a monovalent halogenated hydrocarbon group having 1 to 10 carbonatoms, and X and Y represent independently a hydrogen atom, a monovalenthydrocarbon group having 1 to 10 carbon atoms, a monovalent halogenatedhydrocarbon group having 1 to 10 carbon atoms or an acid-cleavablegroup, provided that at least one of X and Y is an acid-cleavable group,or X and Y are bonded to each other to form a bivalent group representedby the formula:

wherein Z is —O— or —N(R³)— in which R³ is a hydrogen atom, a halogenatom, an alkyl group having 1 to 8 carbon atoms or a —SO₂R⁴ group having1 to 4 carbon atoms in which R⁴ is an alkyl group having 1 to 4 carbonatoms or a halogenated alkyl group having 1 to 4 carbon atoms, or theformula: —O— and (B) a radiation-sensitive acid-generating agent capableof generating an acid upon irradiation with a radiation.
 8. Thecomposition according to claim 7, wherein the acid-cleavable group is agroup: —(CH₂)_(i)COOR¹, —(CH₂)_(i)OCOR² or —(CH₂)_(i)CN wherein R¹ is ahydrocarbon group having 1 to 10 carbon atoms, a halogenated hydrocarbongroup having 1 to 10 carbon atoms, a tetrahydrofuranyl group, atetrahydropyranyl group, a carbobutoxymethyl group, a carbobutoxyethylgroup, a carbobutoxypropyl group or a trialkylsilyl group the alkylgroups of which each have 1 to 4 carbon atoms, R² represents ahydrocarbon group having 1 to 10 carbon atoms or a halogenatedhydrocarbon group having 1 to 10 carbon atoms, and i is an integer of 0to
 4. 9. The composition according to claim 8, wherein theacid-cleavable group is an alkoxycarbonyl group or a cycloalkoxycarbonylgroup.
 10. The composition according to claim 9, wherein theacid-cleavable group is the methoxycarbonyl, ethoxycarbonyl,n-butoxycarbonyl, t-butoxycarbonyl or cyclohexyloxycarbonyl group. 11.The composition according to claim 8, wherein said structure possessedby the copolymer (A) is represented by the general formula (II):

wherein R⁶ is a hydrocarbon group having 1 to 10 carbon atoms, ahalogenated hydrocarbon group having 1 to 10 carbon atoms, atetrahydrofuranyl group, a tetrahydropyranyl group, a carbobutoxymethylgroup, a carbobutoxyethyl group, a carbobutoxypropyl group or atrialkylsilyl group, the alkyl groups of which each have 1 to 4 carbonatoms.
 12. The composition according to claim 11, wherein the R⁶ in thegeneral formula (II) is a methyl, ethyl, n-butyl, t-butyl or cyclohexylgroup.
 13. The radiation-sensitive resin composition according to claim7, wherein the resin (A) has a weight average molecular weight in termsof polystyrene, measured by gel permeation chromatography, of 5,000 to300,000.
 14. The radiation-sensitive resin composition according toclaim 7, wherein the resin (A) has a glass transition point in the rangeof 80 to 180° C.
 15. The radiation-sensitive resin composition accordingto claim 7, wherein the amount of the residual halogen contained in theresin (A) is 3 ppm or less, and the amount of the residual metalcontained therein is 300 ppb or less.
 16. The radiation-sensitive resincomposition according to claim 7, wherein the acid-generating agent (B)is selected from the group consisting of onium salts, halogen-containingcompounds, diazoketone compounds, sulfone compounds, and sulfonic acidcompounds.
 17. The radiation-sensitive resin composition according toclaim 7, wherein the acid-generating agent (B) is present in the amountof 0.1 to 10 parts by weight per 100 parts by weight of the copolymer(A).
 18. A process of producing a copolymer comprising a structurehaving the general formula (I):

wherein n is 0 or 1, A and B represent independently a hydrogen atom, ahalogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atomsor a monovalent halogenated hydrocarbon group having 1 to 10 carbonatoms, and X and Y represent independently a hydrogen atom, a halogenatom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, amonovalent halogenated hydrocarbon group having 1 to 10 carbon atoms oran acid-cleavable group, provided that at least one of X and Y is anacid-cleavable group, or X and Y are bonded to each other to form abivalent group represented by the formula:

wherein Z is —O— or —N(R³)— in which R³ is a hydrogen atom, a hologenatom, an alkyl group having 1 to 8 carbon atoms or a —SO₂R⁴ group having1 to 4 carbon atoms in which R⁴ is an alkyl group having 1 to 4 carbonatoms or a halogenated alkyl group having 1 to 4 carbon atoms, or theformula:

which comprises radical copolymerization of at least one norbornenederivative and maleic acid, wherein the norbornene derivative isrepresented by the following general formula (III):

wherein n, A, B, X and Y are as defined above.
 19. The process accordingto claim 18, wherein said radical polymerization is carried out in thepresence of at least one catalyst selected from the group ofhydroperoxides, dialkylperoxides, diarylperoxides and azo compounds. 20.The process according to claim 18, wherein said radical copolymerizationis carried out in at least one solvent selected from the group ofalkanes, cycloalkanes, aromatic hydrocarbons, halogenated hydrocarbons,saturated carboxylic acid esters and tetrahydrofuran.